Storage Foundation 7.4.1 Administrator's Guide - Linux
- Section I. Introducing Storage Foundation
- Overview of Storage Foundation
- How Dynamic Multi-Pathing works
- How Veritas Volume Manager works
- How Veritas Volume Manager works with the operating system
- How Veritas Volume Manager handles storage management
- Volume layouts in Veritas Volume Manager
- Online relayout
- Volume resynchronization
- Dirty region logging
- Volume snapshots
- FastResync
- How VxVM handles hardware clones or snapshots
- Volume encryption
- How Veritas File System works
- Section II. Provisioning storage
- Provisioning new storage
- Advanced allocation methods for configuring storage
- Customizing allocation behavior
- Using rules to make volume allocation more efficient
- Understanding persistent attributes
- Customizing disk classes for allocation
- Specifying allocation constraints for vxassist operations with the use clause and the require clause
- Creating volumes of a specific layout
- Customizing allocation behavior
- Creating and mounting VxFS file systems
- Creating a VxFS file system
- Mounting a VxFS file system
- tmplog mount option
- ioerror mount option
- largefiles and nolargefiles mount options
- Resizing a file system
- Monitoring free space
- Extent attributes
- Section III. Administering multi-pathing with DMP
- Administering Dynamic Multi-Pathing
- Discovering and configuring newly added disk devices
- About discovering disks and dynamically adding disk arrays
- How to administer the Device Discovery Layer
- Administering DMP using the vxdmpadm utility
- Gathering and displaying I/O statistics
- Specifying the I/O policy
- Discovering and configuring newly added disk devices
- Dynamic Reconfiguration of devices
- Reconfiguring a LUN online that is under DMP control using the Dynamic Reconfiguration tool
- Manually reconfiguring a LUN online that is under DMP control
- Managing devices
- Displaying disk information
- Changing the disk device naming scheme
- Adding and removing disks
- Event monitoring
- Administering Dynamic Multi-Pathing
- Section IV. Administering Storage Foundation
- Administering sites and remote mirrors
- About sites and remote mirrors
- Fire drill - testing the configuration
- Changing the site name
- Administering the Remote Mirror configuration
- Failure and recovery scenarios
- Administering sites and remote mirrors
- Section V. Optimizing I/O performance
- Veritas File System I/O
- Veritas Volume Manager I/O
- Managing application I/O workloads using maximum IOPS settings
- Section VI. Using Point-in-time copies
- Understanding point-in-time copy methods
- When to use point-in-time copies
- About Storage Foundation point-in-time copy technologies
- Volume-level snapshots
- Storage Checkpoints
- About FileSnaps
- About snapshot file systems
- Administering volume snapshots
- Traditional third-mirror break-off snapshots
- Full-sized instant snapshots
- Creating instant snapshots
- Adding an instant snap DCO and DCO volume
- Controlling instant snapshot synchronization
- Creating instant snapshots
- Cascaded snapshots
- Adding a version 0 DCO and DCO volume
- Administering Storage Checkpoints
- Storage Checkpoint administration
- Administering FileSnaps
- Administering snapshot file systems
- Understanding point-in-time copy methods
- Section VII. Optimizing storage with Storage Foundation
- Understanding storage optimization solutions in Storage Foundation
- Migrating data from thick storage to thin storage
- Maintaining Thin Storage with Thin Reclamation
- Reclamation of storage on thin reclamation arrays
- Identifying thin and thin reclamation LUNs
- Veritas InfoScale 4k sector device support solution
- Section VIII. Maximizing storage utilization
- Understanding storage tiering with SmartTier
- Creating and administering volume sets
- Multi-volume file systems
- Features implemented using multi-volume file system (MVFS) support
- Adding a volume to and removing a volume from a multi-volume file system
- Volume encapsulation
- Load balancing
- Administering SmartTier
- About SmartTier
- Placement classes
- Administering placement policies
- File placement policy rules
- Multiple criteria in file placement policy rule statements
- Using SmartTier with solid state disks
- Sub-file relocation
- Administering hot-relocation
- How hot-relocation works
- Moving relocated subdisks
- Deduplicating data
- Compressing files
- About compressing files
- Use cases for compressing files
- Section IX. Administering storage
- Managing volumes and disk groups
- Rules for determining the default disk group
- Moving volumes or disks
- Monitoring and controlling tasks
- Performing online relayout
- Adding a mirror to a volume
- Managing disk groups
- Disk group versions
- Displaying disk group information
- Importing a disk group
- Moving disk groups between systems
- Importing a disk group containing hardware cloned disks
- Handling conflicting configuration copies
- Destroying a disk group
- Backing up and restoring disk group configuration data
- Managing plexes and subdisks
- Decommissioning storage
- Rootability
- Encapsulating a disk
- Rootability
- Sample supported root disk layouts for encapsulation
- Encapsulating and mirroring the root disk
- Administering an encapsulated boot disk
- Quotas
- Using Veritas File System quotas
- File Change Log
- Managing volumes and disk groups
- Section X. Reference
- Appendix A. Reverse path name lookup
- Appendix B. Tunable parameters
- Tuning the VxFS file system
- Methods to change Dynamic Multi-Pathing tunable parameters
- Tunable parameters for VxVM
- Methods to change Veritas Volume Manager tunable parameters
- Appendix C. Command reference
Linked break-off snapshots
A variant of third-mirror break-off snapshots are linked break-off snapshots, which use the vxsnap addmir command to link a specially prepared volume with the data volume. The volume that is used for the snapshot is prepared in the same way as for full-sized instant snapshots. However, unlike full-sized instant snapshots, this volume can be set up in a different disk group from the data volume. This makes linked break-off snapshots especially suitable for recurring off-host processing applications as it avoids the disk group split/join administrative step. As with third-mirror break-off snapshots, you must wait for the contents of the snapshot volume to be synchronized with the data volume before you can use the vxsnap make command to take the snapshot.
When a link is created between a volume and the mirror that will become the snapshot, separate link objects (similar to snap objects) are associated with the volume and with its mirror. The link object for the original volume points to the mirror volume, and the link object for the mirror volume points to the original volume. All I/O is directed to both the original volume and its mirror, and a synchronization of the mirror from the data in the original volume is started.
You can use the vxprint command to display the state of link objects, which appear as type ln. Link objects can have the following states:
The mirror volume has been fully synchronized from the original volume. The vxsnap make command can be run to create a snapshot. | |
Synchronization of the mirror volume is in progress. The vxsnap make command cannot be used to create a snapshot until the state changes to ACTIVE. The vxsnap snapwait command can be used to wait for the synchronization to complete. | |
The mirror volume has been detached from the original volume because of an I/O error or an unsuccessful attempt to grow the mirror volume. The vxrecover command can be used to recover the mirror volume in the same way as for a DISABLED volume. |
If you resize (grow or shrink) a volume, all its ACTIVE linked mirror volumes are also resized at the same time. The volume and its mirrors can be in the same disk group or in different disk groups. If the operation is successful, the volume and its mirrors will have the same size.
If a volume has been grown, a resynchronization of the grown regions in its linked mirror volumes is started, and the links remain in the ATTACHING state until resynchronization is complete. The vxsnap snapwait command can be used to wait for the state to become ACTIVE.
When you use the vxsnap make command to create the snapshot volume, this removes the link, and establishes a snapshot relationship between the snapshot volume and the original volume.
The vxsnap reattach operation re-establishes the link relationship between the two volumes, and starts a resynchronization of the mirror volume.
An empty volume must be prepared for use by linked break-off snapshots.