Veritas™ Volume Manager Administrator's Guide
- Understanding Veritas Volume Manager
- VxVM and the operating system
- How VxVM handles storage management
- Volume layouts in VxVM
- Online relayout
- Volume resynchronization
- Dirty region logging
- Volume snapshots
- FastResync
- Provisioning new usable storage
- Administering disks
- Disk devices
- Discovering and configuring newly added disk devices
- Discovering disks and dynamically adding disk arrays
- How to administer the Device Discovery Layer
- Changing the disk-naming scheme
- Adding a disk to VxVM
- Rootability
- Displaying disk information
- Removing disks
- Removing and replacing disks
- Administering Dynamic Multi-Pathing
- How DMP works
- Administering DMP using vxdmpadm
- Gathering and displaying I/O statistics
- Specifying the I/O policy
- Online dynamic reconfiguration
- Reconfiguring a LUN online that is under DMP control
- Creating and administering disk groups
- About disk groups
- Displaying disk group information
- Creating a disk group
- Importing a disk group
- Moving disk groups between systems
- Handling cloned disks with duplicated identifiers
- Handling conflicting configuration copies
- Reorganizing the contents of disk groups
- Destroying a disk group
- Creating and administering subdisks and plexes
- Displaying plex information
- Reattaching plexes
- Creating volumes
- Types of volume layouts
- Creating a volume
- Using vxassist
- Creating a volume on specific disks
- Creating a mirrored volume
- Creating a striped volume
- Creating a volume using vxmake
- Initializing and starting a volume
- Using rules and persistent attributes to make volume allocation more efficient
- Administering volumes
- Displaying volume information
- Monitoring and controlling tasks
- Reclamation of storage on thin reclamation arrays
- Stopping a volume
- Resizing a volume
- Adding a mirror to a volume
- Preparing a volume for DRL and instant snapshots
- Adding traditional DRL logging to a mirrored volume
- Enabling FastResync on a volume
- Performing online relayout
- Adding a RAID-5 log
- Creating and administering volume sets
- Configuring off-host processing
- Administering hot-relocation
- How hot-relocation works
- Moving relocated subdisks
- Administering cluster functionality (CVM)
- Overview of clustering
- Multiple host failover configurations
- CVM initialization and configuration
- Dirty region logging in cluster environments
- Administering VxVM in cluster environments
- Changing the CVM master manually
- Importing disk groups as shared
- 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
- Performance monitoring and tuning
- Appendix A. Using Veritas Volume Manager commands
- Appendix B. Configuring Veritas Volume Manager
Creating a volume with a version 0 DCO volume
If a data change object (DCO) and DCO volume are associated with a volume, this allows Persistent FastResync to be used with the volume.
The version 0 data change object (DCO) and DCO volume layout was introduced in VxVM 3.2. The version 0 layout supports traditional (third-mirror) snapshots, but not full-sized instant snapshots, space-optimized instant snapshots nor DRL configured within the DCO volume.
To perform fast resynchronization of mirrors after a system crash or reboot, you must also enable dirty region logging (DRL) on a mirrored volume.
For more information about snapshots and DCO volumes, see the Veritas Storage Foundation Advanced Features Administrator's Guide.
Note:
You need a license to use the Persistent FastResync feature. If you do not have a license, you can configure a DCO object and DCO volume so that snap objects are associated with the original and snapshot volumes. However, without a license, only full resynchronization can be performed.
To create a volume with an attached version 0 DCO object and volume
- Ensure that the disk group has been upgraded to at least version 90. Use the following command to check the version of a disk group:
# vxdg list diskgroup
To upgrade a disk group to the latest version, use the following command:
# vxdg upgrade diskgroup
- Use the following command to create the volume (you may need to specify additional attributes to create a volume with the desired characteristics):
# vxassist [-g diskgroup] make volume length layout=layout \ logtype=dco [ndcomirror=number] [dcolen=size] \ [fastresync=on] [other attributes]
For non-layered volumes, the default number of plexes in the mirrored DCO volume is equal to the lesser of the number of plexes in the data volume or 2. For layered volumes, the default number of DCO plexes is always 2. If required, use the ndcomirror attribute to specify a different number. It is recommended that you configure as many DCO plexes as there are data plexes in the volume. For example, specify ndcomirror=3 when creating a 3-way mirrored volume.
The default size of each plex is 132 blocks unless you use the dcolen attribute to specify a different size. If specified, the size of the plex must be a multiple of 33 blocks from 33 up to a maximum of 2112 blocks.
By default, FastResync is not enabled on newly created volumes. Specify the fastresync=on attribute if you want to enable FastResync on the volume. If a DCO object and DCO volume are associated with the volume, Persistent FastResync is enabled; otherwise, Non-Persistent FastResync is enabled.
- To enable DRL or sequential DRL logging on the newly created volume, use the following command:
# vxvol [-g diskgroup] set logtype=drl|drlseq volume
If you use ordered allocation when creating a mirrored volume on specified storage, you can use the optional logdisk attribute to specify on which disks dedicated log plexes should be created. Use the following form of the vxassist command to specify the disks from which space for the logs is to be allocated:
# vxassist [-g diskgroup] -o ordered make volume length \ layout=mirror logtype=log_type logdisk=disk[,disk,...] \ storage_attributes
If you do not specify the logdisk attribute, vxassist locates the logs in the data plexes of the volume.
See Specifying ordered allocation of storage to volumes.
See the vxassist(1M) manual page.
See the vxvol(1M) manual page.