Veritas™ Volume Manager Administrator's Guide

Last Published:
Product(s): InfoScale & Storage Foundation (5.1 SP1)
Platform: HP-UX
  1. Understanding Veritas Volume Manager
    1.  
      About Veritas Volume Manager
    2. VxVM and the operating system
      1.  
        How data is stored
    3. How VxVM handles storage management
      1. Physical objects
        1.  
          Disk arrays
        2.  
          Multiple paths to disk arrays
        3.  
          Device discovery
        4.  
          About enclosure-based naming
      2. Virtual objects
        1.  
          Combining virtual objects in VxVM
        2.  
          Disk groups
        3.  
          VM disks
        4.  
          Subdisks
        5.  
          Plexes
        6.  
          Volumes
    4. Volume layouts in VxVM
      1.  
        Non-layered volumes
      2.  
        Layered volumes
      3.  
        Layout methods
      4.  
        Concatenation, spanning, and carving
      5.  
        Striping (RAID-0)
      6.  
        Mirroring (RAID-1)
      7.  
        Striping plus mirroring (mirrored-stripe or RAID-0+1)
      8.  
        Mirroring plus striping (striped-mirror, RAID-1+0 or RAID-10)
      9. RAID-5 (striping with parity)
        1.  
          Traditional RAID-5 arrays
        2.  
          Veritas Volume Manager RAID-5 arrays
        3.  
          Left-symmetric layout
        4.  
          RAID-5 logging
        5.  
          Layered volumes
    5. Online relayout
      1.  
        How online relayout works
      2.  
        Limitations of online relayout
      3.  
        Transformation characteristics
      4.  
        Transformations and volume length
    6. Volume resynchronization
      1.  
        Dirty flags
      2.  
        Resynchronization process
    7. Dirty region logging
      1.  
        Log subdisks and plexes
      2.  
        Sequential DRL
    8. Volume snapshots
      1.  
        Comparison of snapshot features
    9. FastResync
      1.  
        FastResync enhancements
      2. Non-persistent FastResync
        1.  
          How non-persistent FastResync works with snapshots
      3.  
        Persistent FastResync
      4. DCO volume versioning
        1.  
          Version 0 DCO volume layout
        2.  
          Version 20 DCO volume layout
        3.  
          How persistent FastResync works with snapshots
        4.  
          Effect of growing a volume on the FastResync map
      5.  
        FastResync limitations
    10.  
      Hot-relocation
    11.  
      Volume sets
  2. Provisioning new usable storage
    1.  
      Provisioning new usable storage
    2.  
      Growing the existing storage by adding a new LUN
    3.  
      Growing the existing storage by growing the LUN
  3. Administering disks
    1.  
      About disk management
    2. Disk devices
      1. Disk device naming in VxVM
        1.  
          Operating system-based naming
        2.  
          Enclosure-based naming
      2.  
        Private and public disk regions
    3. Discovering and configuring newly added disk devices
      1.  
        Partial device discovery
      2. Discovering disks and dynamically adding disk arrays
        1.  
          How DMP claims devices
        2.  
          Disk categories
        3.  
          Adding support for a new disk array
        4.  
          Enabling discovery of new disk arrays
      3.  
        Third-party driver coexistence
      4. How to administer the Device Discovery Layer
        1.  
          Listing all the devices including iSCSI
        2.  
          Listing all the Host Bus Adapters including iSCSI
        3.  
          Listing the ports configured on a Host Bus Adapter
        4.  
          Listing the targets configured from a Host Bus Adapter or a port
        5.  
          Listing the devices configured from a Host Bus Adapter and target
        6.  
          Getting or setting the iSCSI operational parameters
        7.  
          Listing all supported disk arrays
        8.  
          Excluding support for a disk array library
        9.  
          Re-including support for an excluded disk array library
        10.  
          Listing excluded disk arrays
        11.  
          Listing supported disks in the DISKS category
        12.  
          Displaying details about a supported array library
        13.  
          Adding unsupported disk arrays to the DISKS category
        14.  
          Removing disks from the DISKS category
        15.  
          Foreign devices
    4.  
      Disks under VxVM control
    5. Changing the disk-naming scheme
      1.  
        Examples of using vxddladm to change the naming scheme
      2.  
        Displaying the disk-naming scheme
      3.  
        Regenerating persistent device names
      4.  
        Changing device naming for TPD-controlled enclosures
      5. Persistent simple or nopriv disks with enclosure-based naming
        1.  
          Removing the error state for persistent simple or nopriv disks in the boot disk group
        2.  
          Removing the error state for persistent simple or nopriv disks in non-boot disk groups
    6.  
      About the Array Volume Identifier (AVID) attribute
    7.  
      Discovering the association between enclosure-based disk names and OS-based disk names
    8.  
      About disk installation and formatting
    9.  
      Displaying or changing default disk layout attributes
    10. Adding a disk to VxVM
      1.  
        Disk reinitialization
      2.  
        Using vxdiskadd to put a disk under VxVM control
    11.  
      RAM disk support in VxVM
    12.  
      Veritas Volume Manager co-existence with Oracle Automatic Storage Management (ASM) disks
    13. Rootability
      1.  
        VxVM root disk volume restrictions
      2.  
        Root disk mirrors
      3.  
        Booting root volumes
      4.  
        Setting up a VxVM root disk and mirror
      5.  
        Creating an LVM root disk from a VxVM root disk
      6.  
        Adding swap volumes to a VxVM rootable system
      7.  
        Adding persistent dump volumes to a VxVM rootable system
      8.  
        Removing a persistent dump volume
    14. Displaying disk information
      1.  
        Displaying disk information with vxdiskadm
    15.  
      Controlling Powerfail Timeout
    16. Removing disks
      1.  
        Removing a disk with subdisks
      2.  
        Removing a disk with no subdisks
    17.  
      Removing a disk from VxVM control
    18. Removing and replacing disks
      1.  
        Replacing a failed or removed disk
    19.  
      Enabling a disk
    20.  
      Taking a disk offline
    21.  
      Renaming a disk
    22.  
      Reserving disks
  4. Administering Dynamic Multi-Pathing
    1. How DMP works
      1. How DMP monitors I/O on paths
        1.  
          Path failover mechanism
        2.  
          Subpaths Failover Group (SFG)
        3.  
          Low Impact Path Probing (LIPP)
        4.  
          I/O throttling
      2.  
        Load balancing
      3. DMP coexistence with HP-UX native multi-pathing
        1.  
          Migrating between DMP and HP-UX native multi-pathing
      4. DMP in a clustered environment
        1.  
          About enabling or disabling controllers with shared disk groups
    2.  
      Disabling multi-pathing and making devices invisible to VxVM
    3.  
      Enabling multi-pathing and making devices visible to VxVM
    4.  
      About enabling and disabling I/O for controllers and storage processors
    5.  
      About displaying DMP database information
    6.  
      Displaying the paths to a disk
    7.  
      Setting customized names for DMP nodes
    8. Administering DMP using vxdmpadm
      1.  
        Retrieving information about a DMP node
      2.  
        Displaying consolidated information about the DMP nodes
      3.  
        Displaying the members of a LUN group
      4.  
        Displaying paths controlled by a DMP node, controller, enclosure, or array port
      5.  
        Displaying information about controllers
      6.  
        Displaying information about enclosures
      7.  
        Displaying information about array ports
      8.  
        Displaying extended device attributes
      9.  
        Suppressing or including devices for VxVM or DMP control
      10. Gathering and displaying I/O statistics
        1.  
          Examples of using the vxdmpadm iostat command
        2.  
          Displaying statistics for queued or erroneous I/Os
        3.  
          Displaying cumulative I/O statistics
      11.  
        Setting the attributes of the paths to an enclosure
      12.  
        Displaying the redundancy level of a device or enclosure
      13.  
        Specifying the minimum number of active paths
      14.  
        Displaying the I/O policy
      15. Specifying the I/O policy
        1.  
          Scheduling I/O on the paths of an Asymmetric Active/Active array
        2.  
          Example of applying load balancing in a SAN
      16.  
        Disabling I/O for paths, controllers or array ports
      17.  
        Enabling I/O for paths, controllers or array ports
      18.  
        Renaming an enclosure
      19.  
        Configuring the response to I/O failures
      20.  
        Configuring the I/O throttling mechanism
      21.  
        Configuring Subpaths Failover Groups (SFG)
      22.  
        Configuring Low Impact Path Probing
      23.  
        Displaying recovery option values
      24.  
        Configuring DMP path restoration policies
      25.  
        Stopping the DMP path restoration thread
      26.  
        Displaying the status of the DMP path restoration thread
      27.  
        Displaying information about the DMP error-handling thread
      28.  
        Configuring array policy modules
  5. Online dynamic reconfiguration
    1.  
      About online dynamic reconfiguration
    2. Reconfiguring a LUN online that is under DMP control
      1.  
        Removing LUNs dynamically from an existing target ID
      2.  
        Adding new LUNs dynamically to a new target ID
      3.  
        About detecting target ID reuse if the operating system device tree is not cleaned up
      4.  
        Scanning an operating system device tree after adding or removing LUNs
      5.  
        Cleaning up the operating system device tree after removing LUNs
    3.  
      Upgrading the array controller firmware online
    4.  
      Replacing a host bus adapter
  6. Creating and administering disk groups
    1. About disk groups
      1.  
        Specification of disk groups to commands
      2.  
        System-wide reserved disk groups
      3. Rules for determining the default disk group
        1.  
          Displaying the system-wide boot disk group
        2.  
          Displaying and specifying the system-wide default disk group
      4.  
        Disk group versions
    2. Displaying disk group information
      1.  
        Displaying free space in a disk group
    3. Creating a disk group
      1.  
        Creating a disk group with an earlier disk group version
    4.  
      Adding a disk to a disk group
    5.  
      Removing a disk from a disk group
    6.  
      Moving disks between disk groups
    7.  
      Deporting a disk group
    8. Importing a disk group
      1.  
        Setting the automatic recovery of volumes
    9.  
      Handling of minor number conflicts
    10. Moving disk groups between systems
      1.  
        Handling errors when importing disks
      2.  
        Reserving minor numbers for disk groups
      3.  
        Compatibility of disk groups between platforms
    11. Handling cloned disks with duplicated identifiers
      1.  
        Writing a new UDID to a disk
      2.  
        Importing a disk group containing cloned disks
      3. Sample cases of operations on cloned disks
        1.  
          Enabling configuration database copies on tagged disks
        2.  
          Importing cloned disks without tags
        3.  
          Importing cloned disks with tags
      4.  
        Considerations when using EMC CLARiiON SNAPSHOT LUNs
    12.  
      Renaming a disk group
    13. Handling conflicting configuration copies
      1.  
        Example of a serial split brain condition in a cluster
      2.  
        Correcting conflicting configuration information
    14. Reorganizing the contents of disk groups
      1.  
        Limitations of disk group split and join
      2. Listing objects potentially affected by a move
        1.  
          Moving DCO volumes between disk groups
      3.  
        Moving objects between disk groups
      4.  
        Splitting disk groups
      5.  
        Joining disk groups
    15.  
      Disabling a disk group
    16. Destroying a disk group
      1.  
        Recovering a destroyed disk group
    17.  
      Upgrading the disk group version
    18.  
      About the configuration daemon in VxVM
    19.  
      Backing up and restoring disk group configuration data
    20.  
      Using vxnotify to monitor configuration changes
    21.  
      Working with existing ISP disk groups
  7. Creating and administering subdisks and plexes
    1.  
      About subdisks
    2.  
      Creating subdisks
    3.  
      Displaying subdisk information
    4.  
      Moving subdisks
    5.  
      Splitting subdisks
    6.  
      Joining subdisks
    7.  
      Associating subdisks with plexes
    8.  
      Associating log subdisks
    9.  
      Dissociating subdisks from plexes
    10.  
      Removing subdisks
    11.  
      Changing subdisk attributes
    12.  
      About plexes
    13.  
      Creating plexes
    14.  
      Creating a striped plex
    15. Displaying plex information
      1.  
        Plex states
      2.  
        Plex condition flags
      3.  
        Plex kernel states
    16.  
      Attaching and associating plexes
    17.  
      Taking plexes offline
    18.  
      Detaching plexes
    19. Reattaching plexes
      1.  
        Automatic plex reattachment
    20.  
      Moving plexes
    21.  
      Copying volumes to plexes
    22.  
      Dissociating and removing plexes
    23.  
      Changing plex attributes
  8. Creating volumes
    1.  
      About volume creation
    2. Types of volume layouts
      1.  
        Supported volume logs and maps
    3. Creating a volume
      1.  
        Advanced approach
      2.  
        Assisted approach
    4. Using vxassist
      1.  
        Setting default values for vxassist
      2.  
        Using the SmartMove™ feature while attaching a plex
    5.  
      Discovering the maximum size of a volume
    6.  
      Disk group alignment constraints on volumes
    7.  
      Creating a volume on any disk
    8. Creating a volume on specific disks
      1.  
        Creating a volume on SSD devices
      2.  
        Specifying ordered allocation of storage to volumes
    9. Creating a mirrored volume
      1.  
        Creating a mirrored-concatenated volume
      2.  
        Creating a concatenated-mirror volume
    10.  
      Creating a volume with a version 0 DCO volume
    11.  
      Creating a volume with a version 20 DCO volume
    12.  
      Creating a volume with dirty region logging enabled
    13. Creating a striped volume
      1.  
        Creating a mirrored-stripe volume
      2.  
        Creating a striped-mirror volume
    14.  
      Mirroring across targets, controllers or enclosures
    15.  
      Mirroring across media types (SSD and HDD)
    16.  
      Creating a RAID-5 volume
    17.  
      Creating tagged volumes
    18. Creating a volume using vxmake
      1.  
        Creating a volume using a vxmake description file
    19. Initializing and starting a volume
      1.  
        Initializing and starting a volume created using vxmake
    20.  
      Accessing a volume
    21. Using rules and persistent attributes to make volume allocation more efficient
      1.  
        Understanding persistent attributes
      2.  
        Rule file format
      3.  
        Using rules to create a volume
      4.  
        Using persistent attributes
  9. Administering volumes
    1.  
      About volume administration
    2. Displaying volume information
      1.  
        Volume states
      2.  
        Volume kernel states
    3. Monitoring and controlling tasks
      1.  
        Specifying task tags
      2. Managing tasks with vxtask
        1.  
          vxtask operations
        2.  
          Using the vxtask command
    4.  
      About SF Thin Reclamation feature
    5. Reclamation of storage on thin reclamation arrays
      1.  
        Identifying thin and thin reclamation LUNs
      2.  
        How reclamation on a deleted volume works
      3.  
        Thin Reclamation of a disk, a disk group, or an enclosure
      4.  
        Thin Reclamation of a file system
      5.  
        Triggering space reclamation
    6.  
      Monitoring Thin Reclamation using the vxtask command
    7.  
      Using SmartMove with Thin Provisioning
    8.  
      Admin operations on an unmounted VxFS thin volume
    9. Stopping a volume
      1.  
        Putting a volume in maintenance mode
    10.  
      Starting a volume
    11. Resizing a volume
      1.  
        Resizing volumes with vxresize
      2. Resizing volumes with vxassist
        1.  
          Extending to a given length
        2.  
          Extending by a given length
        3.  
          Shrinking to a given length
        4.  
          Shrinking by a given length
      3.  
        Resizing volumes with vxvol
    12. Adding a mirror to a volume
      1.  
        Mirroring all volumes
      2.  
        Mirroring volumes on a VM disk
    13.  
      Removing a mirror
    14.  
      Adding logs and maps to volumes
    15. Preparing a volume for DRL and instant snapshots
      1.  
        Specifying storage for version 20 DCO plexes
      2.  
        Using a DCO and DCO volume with a RAID-5 volume
      3.  
        Determining the DCO version number
      4.  
        Determining if DRL is enabled on a volume
      5.  
        Determining if DRL logging is active on a volume
      6.  
        Disabling and re-enabling DRL
      7.  
        Removing support for DRL and instant snapshots from a volume
    16. Adding traditional DRL logging to a mirrored volume
      1.  
        Removing a traditional DRL log
    17.  
      Upgrading existing volumes to use version 20 DCOs
    18.  
      Setting tags on volumes
    19.  
      Changing the read policy for mirrored volumes
    20.  
      Removing a volume
    21.  
      Moving volumes from a VM disk
    22. Enabling FastResync on a volume
      1.  
        Checking whether FastResync is enabled on a volume
      2.  
        Disabling FastResync
    23. Performing online relayout
      1.  
        Permitted relayout transformations
      2.  
        Specifying a non-default layout
      3.  
        Specifying a plex for relayout
      4.  
        Tagging a relayout operation
      5.  
        Viewing the status of a relayout
      6.  
        Controlling the progress of a relayout
    24.  
      Converting between layered and non-layered volumes
    25. Adding a RAID-5 log
      1.  
        Adding a RAID-5 log using vxplex
      2.  
        Removing a RAID-5 log
  10. Creating and administering volume sets
    1.  
      About volume sets
    2.  
      Creating a volume set
    3.  
      Adding a volume to a volume set
    4.  
      Removing a volume from a volume set
    5.  
      Listing details of volume sets
    6.  
      Stopping and starting volume sets
    7. Raw device node access to component volumes
      1.  
        Enabling raw device access when creating a volume set
      2.  
        Displaying the raw device access settings for a volume set
      3.  
        Controlling raw device access for an existing volume set
  11. Configuring off-host processing
    1.  
      About off-host processing solutions
    2. Implemention of off-host processing solutions
      1.  
        Implementing off-host online backup
      2.  
        Implementing decision support
  12. Administering hot-relocation
    1.  
      About hot-relocation
    2. How hot-relocation works
      1.  
        Partial disk failure mail messages
      2.  
        Complete disk failure mail messages
      3.  
        How space is chosen for relocation
    3.  
      Configuring a system for hot-relocation
    4.  
      Displaying spare disk information
    5.  
      Marking a disk as a hot-relocation spare
    6.  
      Removing a disk from use as a hot-relocation spare
    7.  
      Excluding a disk from hot-relocation use
    8.  
      Making a disk available for hot-relocation use
    9.  
      Configuring hot-relocation to use only spare disks
    10. Moving relocated subdisks
      1.  
        Moving relocated subdisks using vxdiskadm
      2.  
        Moving relocated subdisks using vxassist
      3. Moving relocated subdisks using vxunreloc
        1.  
          Moving hot-relocated subdisks back to their original disk
        2.  
          Moving hot-relocated subdisks back to a different disk
        3.  
          Forcing hot-relocated subdisks to accept different offsets
        4.  
          Examining which subdisks were hot-relocated from a disk
      4.  
        Restarting vxunreloc after errors
    11.  
      Modifying the behavior of hot-relocation
  13. Administering cluster functionality (CVM)
    1. Overview of clustering
      1.  
        Overview of cluster volume management
      2.  
        Private and shared disk groups
      3.  
        Activation modes of shared disk groups
      4. Connectivity policy of shared disk groups
        1.  
          Global detach policy
        2.  
          Local detach policy
        3.  
          Guidelines for choosing detach policies
        4.  
          Disk group failure policy
        5.  
          Guidelines for failure policies
      5.  
        Effect of disk connectivity on cluster reconfiguration
      6.  
        Limitations of shared disk groups
    2. Multiple host failover configurations
      1.  
        Import lock
      2.  
        Failover
      3.  
        Corruption of disk group configuration
    3.  
      About the cluster functionality of VxVM
    4. CVM initialization and configuration
      1. Cluster reconfiguration
        1.  
          vxclustadm utility
      2. Volume reconfiguration
        1.  
          vxconfigd daemon
        2.  
          vxconfigd daemon recovery
      3.  
        Node shutdown
      4.  
        Cluster shutdown
    5. Dirty region logging in cluster environments
      1.  
        How DRL works in a cluster environment
    6. Administering VxVM in cluster environments
      1.  
        Requesting node status and discovering the master node
      2. Changing the CVM master manually
        1.  
          Errors during CVM master switching
      3.  
        Determining if a LUN is in a shareable disk group
      4.  
        Listing shared disk groups
      5.  
        Creating a shared disk group
      6. Importing disk groups as shared
        1.  
          Forcibly importing a disk group
      7.  
        Handling cloned disks in a shared disk group
      8.  
        Converting a disk group from shared to private
      9.  
        Moving objects between shared disk groups
      10.  
        Splitting shared disk groups
      11.  
        Joining shared disk groups
      12.  
        Changing the activation mode on a shared disk group
      13.  
        Setting the disk detach policy on a shared disk group
      14.  
        Setting the disk group failure policy on a shared disk group
      15.  
        Creating volumes with exclusive open access by a node
      16.  
        Setting exclusive open access to a volume by a node
      17.  
        Displaying the cluster protocol version
      18.  
        Displaying the supported cluster protocol version range
      19.  
        Recovering volumes in shared disk groups
      20.  
        Obtaining cluster performance statistics
      21.  
        Administering CVM from the slave node
  14. Administering sites and remote mirrors
    1. About sites and remote mirrors
      1.  
        About site-based allocation
      2.  
        About site consistency
      3.  
        About site tags
      4.  
        About the site read policy
    2.  
      Making an existing disk group site consistent
    3.  
      Configuring a new disk group as a Remote Mirror configuration
    4. Fire drill - testing the configuration
      1.  
        Simulating site failure
      2.  
        Verifying the secondary site
      3.  
        Recovery from simulated site failure
    5. Changing the site name
      1.  
        Resetting the site name for a host
    6. Administering the Remote Mirror configuration
      1.  
        Configuring site tagging for disks or enclosures
      2.  
        Configuring automatic site tagging for a disk group
      3.  
        Configuring site consistency on a volume
    7.  
      Examples of storage allocation by specifying sites
    8.  
      Displaying site information
    9. Failure and recovery scenarios
      1.  
        Recovering from a loss of site connectivity
      2.  
        Recovering from host failure
      3.  
        Recovering from storage failure
      4.  
        Recovering from site failure
      5.  
        Automatic site reattachment
  15. Performance monitoring and tuning
    1. Performance guidelines
      1.  
        Data assignment
      2.  
        Striping
      3.  
        Mirroring
      4.  
        Combining mirroring and striping
    2. RAID-5
      1.  
        Volume read policies
    3. Performance monitoring
      1.  
        Setting performance priorities
      2. Obtaining performance data
        1.  
          Tracing volume operations
        2.  
          Printing volume statistics
      3. Using performance data
        1.  
          Using I/O statistics
        2.  
          Using I/O tracing
    4. Tuning VxVM
      1.  
        General tuning guidelines
      2. Tuning guidelines for large systems
        1.  
          Number of configuration copies for a disk group
      3.  
        Changing the values of VxVM tunables
      4.  
        Tunable parameters for VxVM
      5.  
        DMP tunable parameters
      6.  
        Disabling I/O statistics collection
      7.  
        Enabling I/O statistics collection
  16. Appendix A. Using Veritas Volume Manager commands
    1.  
      About Veritas Volume Manager commands
    2.  
      CVM commands supported for executing on the slave node
    3. Online manual pages
      1.  
        Section 1M - administrative commands
      2.  
        Section 4 - file formats
      3.  
        Section 7 - device driver interfaces
  17. Appendix B. Configuring Veritas Volume Manager
    1.  
      Setup tasks after installation
    2.  
      Unsupported disk arrays
    3.  
      Foreign devices
    4.  
      Initialization of disks and creation of disk groups
    5. Guidelines for configuring storage
      1.  
        Mirroring guidelines
      2.  
        Dirty region logging guidelines
      3.  
        Striping guidelines
      4.  
        RAID-5 guidelines
      5.  
        Hot-relocation guidelines
      6.  
        Accessing volume devices
    6.  
      VxVM's view of multipathed devices
    7. Cluster support
      1.  
        Configuring shared disk groups
      2.  
        Converting existing VxVM disk groups to shared disk groups
  18.  
    Glossary

Glossary

Active/Active disk arrays

This type of multi-pathed disk array allows you to access a disk in the disk array through all the paths to the disk simultaneously, without any performance degradation.

Active/Passive disk arrays

This type of multipathed disk array allows one path to a disk to be designated as primary and used to access the disk at any time. Using a path other than the designated active path results in severe performance degradation in some disk arrays.

associate

The process of establishing a relationship between VxVM objects; for example, a subdisk that has been created and defined as having a starting point within a plex is referred to as being associated with that plex.

associated plex

A plex associated with a volume.

associated subdisk

A subdisk associated with a plex.

atomic operation

An operation that either succeeds completely or fails and leaves everything as it was before the operation was started. If the operation succeeds, all aspects of the operation take effect at once and the intermediate states of change are invisible. If any aspect of the operation fails, then the operation aborts without leaving partial changes.

In a cluster, an atomic operation takes place either on all nodes or not at all.

attached

A state in which a VxVM object is both associated with another object and enabled for use.

block

The minimum unit of data transfer to or from a disk or array.

boot disk

A disk that is used for the purpose of booting a system.

boot disk group

A private disk group that contains the disks from which the system may be booted.

bootdg

A reserved disk group name that is an alias for the name of the boot disk group.

clean node shutdown

The ability of a node to leave a cluster gracefully when all access to shared volumes has ceased.

cluster

A set of hosts (each termed a node) that share a set of disks.

cluster manager

An externally-provided daemon that runs on each node in a cluster. The cluster managers on each node communicate with each other and inform VxVM of changes in cluster membership.

cluster-shareable disk group

A disk group in which access to the disks is shared by multiple hosts (also referred to as a shared disk group).

column

A set of one or more subdisks within a striped plex. Striping is achieved by allocating data alternately and evenly across the columns within a plex.

concatenation

A layout style characterized by subdisks that are arranged sequentially and contiguously.

configuration copy

A single copy of a configuration database.

configuration database

A set of records containing detailed information on existing VxVM objects (such as disk and volume attributes).

DCO (data change object)

A VxVM object that is used to manage information about the FastResync maps in the DCO volume. Both a DCO object and a DCO volume must be associated with a volume to implement Persistent FastResync on that volume.

data stripe

This represents the usable data portion of a stripe and is equal to the stripe minus the parity region.

DCO volume

A special volume that is used to hold Persistent FastResync change maps and dirty region logs. See also see dirty region logging.

detached

A state in which a VxVM object is associated with another object, but not enabled for use.

device name

The device name or address used to access a physical disk, such as c0t0d0. The c#t#d# syntax identifies the controller, target address, and disk.

In a SAN environment, it is more convenient to use enclosure-based naming, which forms the device name by concatenating the name of the enclosure (such as enc0) with the disk's number within the enclosure, separated by an underscore (for example, enc0_2). The term disk access name can also be used to refer to a device name.

dirty region logging

The method by which the VxVM monitors and logs modifications to a plex as a bitmap of changed regions. For a volumes with a new-style DCO volume, the dirty region log (DRL) is maintained in the DCO volume. Otherwise, the DRL is allocated to an associated subdisk called a log subdisk.

disabled path

A path to a disk that is not available for I/O. A path can be disabled due to real hardware failures or if the user has used the vxdmpadm disable command on that controller.

disk

A collection of read/write data blocks that are indexed and can be accessed fairly quickly. Each disk has a universally unique identifier.

disk access name

An alternative term for a device name.

disk access records

Configuration records used to specify the access path to particular disks. Each disk access record contains a name, a type, and possibly some type-specific information, which is used by VxVM in deciding how to access and manipulate the disk that is defined by the disk access record.

disk array

A collection of disks logically arranged into an object. Arrays tend to provide benefits such as redundancy or improved performance.

disk array serial number

This is the serial number of the disk array. It is usually printed on the disk array cabinet or can be obtained by issuing a vendor- specific SCSI command to the disks on the disk array. This number is used by the DMP subsystem to uniquely identify a disk array.

disk controller

In the multi-pathing subsystem of VxVM, the controller (host bus adapter or HBA) or disk array connected to the host, which the operating system represents as the parent node of a disk.

disk enclosure

An intelligent disk array that usually has a backplane with a built-in Fibre Channel loop, and which permits hot-swapping of disks.

disk group

A collection of disks that share a common configuration. A disk group configuration is a set of records containing detailed information on existing VxVM objects (such as disk and volume attributes) and their relationships. Each disk group has an administrator-assigned name and an internally defined unique ID. The disk group names bootdg (an alias for the boot disk group), defaultdg (an alias for the default disk group) and nodg (represents no disk group) are reserved.

disk group ID

A unique identifier used to identify a disk group.

disk ID

A universally unique identifier that is given to each disk and can be used to identify the disk, even if it is moved.

disk media name

An alternative term for a disk name.

disk media record

A configuration record that identifies a particular disk, by disk ID, and gives that disk a logical (or administrative) name.

disk name

A logical or administrative name chosen for a disk that is under the control of VxVM, such as disk03. The term disk media name is also used to refer to a disk name.

dissociate

The process by which any link that exists between two VxVM objects is removed. For example, dissociating a subdisk from a plex removes the subdisk from the plex and adds the subdisk to the free space pool.

dissociated plex

A plex dissociated from a volume.

dissociated subdisk

A subdisk dissociated from a plex.

distributed lock manager

A lock manager that runs on different systems in a cluster, and ensures consistent access to distributed resources.

enabled path

A path to a disk that is available for I/O.

encapsulation

A process that converts existing partitions on a specified disk to volumes.

Encapsulation is not supported on the HP-UX platform.

enclosure

See disk enclosure.

enclosure-based naming

See device name.

fabric mode disk

A disk device that is accessible on a Storage Area Network (SAN) via a Fibre Channel switch.

FastResync

A fast resynchronization feature that is used to perform quick and efficient resynchronization of stale mirrors, and to increase the efficiency of the snapshot mechanism.

Fibre Channel

A collective name for the fiber optic technology that is commonly used to set up a Storage Area Network (SAN).

file system

A collection of files organized together into a structure. The UNIX file system is a hierarchical structure consisting of directories and files.

free space

An area of a disk under VxVM control that is not allocated to any subdisk or reserved for use by any other VxVM object.

free subdisk

A subdisk that is not associated with any plex and has an empty putil[0] field.

hostid

A string that identifies a host to VxVM. The host ID for a host is stored in its volboot file, and is used in defining ownership of disks and disk groups.

hot-relocation

A technique of automatically restoring redundancy and access to mirrored and RAID-5 volumes when a disk fails. This is done by relocating the affected subdisks to disks designated as spares and/or free space in the same disk group.

hot-swap

Refers to devices that can be removed from, or inserted into, a system without first turning off the power supply to the system.

initiating node

The node on which the system administrator is running a utility that requests a change to VxVM objects. This node initiates a volume reconfiguration.

JBOD (just a bunch of disks)

The common name for an unintelligent disk array which may, or may not, support the hot-swapping of disks.

log plex

A plex used to store a RAID-5 log. The term log plex may also be used to refer to a Dirty Region Logging plex.

log subdisk

A subdisk that is used to store a dirty region log.

master node

A node that is designated by the software to coordinate certain VxVM operations in a cluster. Any node is capable of being the master node.

mastering node

The node to which a disk is attached. This is also known as a disk owner.

mirror

A duplicate copy of a volume and the data therein (in the form of an ordered collection of subdisks). Each mirror consists of one plex of the volume with which the mirror is associated.

mirroring

A layout technique that mirrors the contents of a volume onto multiple plexes. Each plex duplicates the data stored on the volume, but the plexes themselves may have different layouts.

multi-pathing

Where there are multiple physical access paths to a disk connected to a system, the disk is called multi-pathed. Any software residing on the host, (for example, the DMP driver) that hides this fact from the user is said to provide multi-pathing functionality.

node

One of the hosts in a cluster.

node abort

A situation where a node leaves a cluster (on an emergency basis) without attempting to stop ongoing operations.

node join

The process through which a node joins a cluster and gains access to shared disks.

Non-Persistent FastResync

A form of FastResync that cannot preserve its maps across reboots of the system because it stores its change map in memory.

object

An entity that is defined to and recognized internally by VxVM. The VxVM objects are: volume, plex, subdisk, disk, and disk group. There are actually two types of disk objects - one for the physical aspect of the disk and the other for the logical aspect.

parity

A calculated value that can be used to reconstruct data after a failure. While data is being written to a RAID-5 volume, parity is also calculated by performing an exclusive OR (XOR) procedure on data. The resulting parity is then written to the volume. If a portion of a RAID-5 volume fails, the data that was on that portion of the failed volume can be recreated from the remaining data and the parity.

parity stripe unit

A RAID-5 volume storage region that contains parity information. The data contained in the parity stripe unit can be used to help reconstruct regions of a RAID-5 volume that are missing because of I/O or disk failures.

partition

The standard division of a physical disk device, as supported directly by the operating system and disk drives.

path

When a disk is connected to a host, the path to the disk consists of the HBA (Host Bus Adapter) on the host, the SCSI or fibre cable connector and the controller on the disk or disk array. These components constitute a path to a disk. A failure on any of these results in DMP trying to shift all I/O for that disk onto the remaining (alternate) paths.

pathgroup

In the case of disks which are not multipathed by vxdmp, VxVM will see each path as a disk. In such cases, all paths to the disk can be grouped. This way only one of the paths from the group is made visible to VxVM.

Persistent FastResync

A form of FastResync that can preserve its maps across reboots of the system by storing its change map in a DCO volume on disk).

persistent state logging

A logging type that ensures that only active mirrors are used for recovery purposes and prevents failed mirrors from being selected for recovery. This is also known as kernel logging.

physical disk

The underlying storage device, which may or may not be under VxVM control.

plex

A plex is a logical grouping of subdisks that creates an area of disk space independent of physical disk size or other restrictions. Mirroring is set up by creating multiple data plexes for a single volume. Each data plex in a mirrored volume contains an identical copy of the volume data. Plexes may also be created to represent concatenated, striped and RAID-5 volume layouts, and to store volume logs.

primary path

In Active/Passive disk arrays, a disk can be bound to one particular controller on the disk array or owned by a controller. The disk can then be accessed using the path through this particular controller.

private disk group

A disk group in which the disks are accessed by only one specific host in a cluster.

private region

A region of a physical disk used to store private, structured VxVM information. The private region contains a disk header, a table of contents, and a configuration database. The table of contents maps the contents of the disk. The disk header contains a disk ID. All data in the private region is duplicated for extra reliability.

public region

A region of a physical disk managed by VxVM that contains available space and is used for allocating subdisks.

RAID (redundant array of independent disks)

A disk array set up with part of the combined storage capacity used for storing duplicate information about the data stored in that array. This makes it possible to regenerate the data if a disk failure occurs.

read-writeback mode

A recovery mode in which each read operation recovers plex consistency for the region covered by the read. Plex consistency is recovered by reading data from blocks of one plex and writing the data to all other writable plexes.

root configuration

The configuration database for the root disk group. This is special in that it always contains records for other disk groups, which are used for backup purposes only. It also contains disk records that define all disk devices on the system.

root disk

The disk containing the root file system. This disk may be under VxVM control.

root file system

The initial file system mounted as part of the UNIX kernel startup sequence.

root partition

The disk region on which the root file system resides.

root volume

The VxVM volume that contains the root file system, if such a volume is designated by the system configuration.

rootability

The ability to place the root file system and the swap device under VxVM control. The resulting volumes can then be mirrored to provide redundancy and allow recovery in the event of disk failure.

secondary path

In Active/Passive disk arrays, the paths to a disk other than the primary path are called secondary paths. A disk is supposed to be accessed only through the primary path until it fails, after which ownership of the disk is transferred to one of the secondary paths.

sector

A unit of size, which can vary between systems. Sector size is set per device (hard drive, CD-ROM, and so on). Although all devices within a system are usually configured to the same sector size for interoperability, this is not always the case.

A sector is commonly 1024 bytes.

shared disk group

A disk group in which access to the disks is shared by multiple hosts (also referred to as a cluster-shareable disk group).

shared volume

A volume that belongs to a shared disk group and is open on more than one node of a cluster at the same time.

shared VM disk

A VM disk that belongs to a shared disk group in a cluster.

slave node

A node that is not designated as the master node of a cluster.

slice

The standard division of a logical disk device. The terms partition and slice are sometimes used synonymously.

snapshot

A point-in-time copy of a volume (volume snapshot) or a file system (file system snapshot).

spanning

A layout technique that permits a volume (and its file system or database) that is too large to fit on a single disk to be configured across multiple physical disks.

sparse plex

A plex that is not as long as the volume or that has holes (regions of the plex that do not have a backing subdisk).

SAN (storage area network)

A networking paradigm that provides easily reconfigurable connectivity between any subset of computers, disk storage and interconnecting hardware such as switches, hubs and bridges.

stripe

A set of stripe units that occupy the same positions across a series of columns.

stripe size

The sum of the stripe unit sizes comprising a single stripe across all columns being striped.

stripe unit

Equally-sized areas that are allocated alternately on the subdisks (within columns) of each striped plex. In an array, this is a set of logically contiguous blocks that exist on each disk before allocations are made from the next disk in the array. A stripe unit may also be referred to as a stripe element.

stripe unit size

The size of each stripe unit. The default stripe unit size is 64KB. The stripe unit size is sometimes also referred to as the stripe width.

striping

A layout technique that spreads data across several physical disks using stripes. The data is allocated alternately to the stripes within the subdisks of each plex.

subdisk

A consecutive set of contiguous disk blocks that form a logical disk segment. Subdisks can be associated with plexes to form volumes.

swap area

A disk region used to hold copies of memory pages swapped out by the system pager process.

swap volume

A VxVM volume that is configured for use as a swap area.

transaction

A set of configuration changes that succeed or fail as a group, rather than individually. Transactions are used internally to maintain consistent configurations.

VM disk

A disk that is both under VxVM control and assigned to a disk group. VM disks are sometimes referred to as VxVM disks.

volboot file

A small file that is used to locate copies of the boot disk group configuration. The file may list disks that contain configuration copies in standard locations, and can also contain direct pointers to configuration copy locations. The volboot file is stored in a system-dependent location.

volume

A virtual disk, representing an addressable range of disk blocks used by applications such as file systems or databases. A volume is a collection of from one to 32 plexes.

volume configuration device

The volume configuration device (/dev/vx/config) is the interface through which all configuration changes to the volume device driver are performed.

volume device driver

The driver that forms the virtual disk drive between the application and the physical device driver level. The volume device driver is accessed through a virtual disk device node whose character device nodes appear in /dev/vx/rdsk, and whose block device nodes appear in /dev/vx/dsk.

volume event log

The device interface (/dev/vx/event) through which volume driver events are reported to utilities.

vxconfigd

The VxVM configuration daemon, which is responsible for making changes to the VxVM configuration. This daemon must be running before VxVM operations can be performed.