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
Implementing off-host online backup
This section describes a procedure for implementing off-host online backup for a volume in a private disk group. It outlines how to set up a regular backup cycle. It is beyond the scope of this guide to describe how to configure a database to use this procedure, or how to perform the backup itself.
To back up a volume in a private disk group
- On the primary host, use the following command to see if the volume is associated with a version 20 data change object (DCO) and DCO volume that allow instant snapshots and Persistent FastResync to be used with the volume:
# vxprint -g volumedg -F%instant volume
If the volume can be used for instant snapshot operations, this command returns on; otherwise, it returns off.
If the volume was created under VxVM 4.0 or a later release, and it is not associated with a new-style DCO object and DCO volume, add a version 20 DCO and DCO volume.
See Preparing a volume for DRL and instant snapshots.
If the volume was created before release 4.0 of VxVM, and has any attached snapshot plexes, or is associated with any snapshot volumes, upgrade the volume to use a version 20 DCO.
- On the primary host, use the following command to check whether FastResync is enabled on the volume:
# vxprint -g volumedg -F%fastresync volume
If FastResync is enabled, this command returns on; otherwise, it returns off.
If FastResync is disabled, enable it using the following command on the primary host:
# vxvol -g volumedg set fastresync=on volume
- On the primary host, create a new volume in a separate disk group for use as the snapshot volume.
For more information about snapshots, see the Veritas Storage Foundation Advanced Features Administrator's Guide.
It is recommended that a snapshot disk group is dedicated to maintaining only those disks that are used for off-host processing.
- On the primary host, link the snapshot volume in the snapshot disk group to the data volume. Enter the following:
# vxsnap -g volumedg -b addmir volume mirvol=snapvol \ mirdg=snapvoldg
You can use the vxsnap snapwait command to wait for synchronization of the linked snapshot volume to complete. Enter the following:
# vxsnap -g volumedg snapwait volume mirvol=snapvol \ mirdg=snapvoldg
This step sets up the snapshot volumes, and starts tracking changes to the original volumes.
When you are ready to create a backup, go to step 5.
- On the primary host, suspend updates to the volume that contains the database tables. A database may have a hot backup mode that lets you do this by temporarily suspending writes to its tables.
- On the primary host, create the snapshot volume, snapvol, by running the following command:
# vxsnap -g volumedg make \ source=volume/snapvol=snapvol/snapdg=snapvoldg
If a database spans more than one volume, you can specify all the volumes and their snapshot volumes using one command, as follows:
# vxsnap -g dbasedg make \ source=vol1/snapvol=snapvol1/snapdg=sdg \ source=vol2/snapvol=snapvol2/snapdg=sdg \ source=vol3/snapvol=snapvol3/snapdg=sdg
- On the primary host, if you temporarily suspended updates to a volume in step 5, release all the database tables from hot backup mode.
- On the primary host, deport the snapshot volume's disk group using the following command:
# vxdg deport snapvoldg
- On the OHP host where the backup is to be performed, use the following command to import the snapshot volume's disk group:
# vxdg import snapvoldg
- The snapshot volume is initially disabled following the import. On the OHP host, use the following commands to recover and restart the snapshot volume:
# vxrecover -g snapvoldg -m snapvol # vxvol -g snapvoldg start snapvol
- On the OHP host, back up the snapshot volume. If you need to remount the file system in the volume to back it up, first run fsck on the volume. The following are sample commands for checking and mounting a file system:
# fsck -F vxfs /dev/vx/rdsk/snapvoldg/snapvol # mount -F vxfs /dev/vx/dsk/snapvoldg/snapvol mount_point
At this point, back up the file system and use the following command to unmount it:
# umount mount_point
- On the OHP host, use the following command to deport the snapshot volume's disk group:
# vxdg deport snapvoldg
- On the primary host, re-import the snapshot volume's disk group using the following command:
# vxdg import snapvoldg
- The snapshot volume is initially disabled following the import. Use the following commands on the primary host to recover and restart the snapshot volume:
# vxrecover -g snapvoldg -m snapvol # vxvol -g snapvoldg start snapvol
- On the primary host, reattach the snapshot volume to its original volume using the following command:
# vxsnap -g snapvoldg reattach snapvol source=vol \ sourcedg=volumedg
For example, to reattach the snapshot volumes svol1, svol2 and svol3:
# vxsnap -g sdg reattach svol1 \ source=vol1 sourcedg=dbasedg \ svol2 source=vol2 sourcedg=dbasedg \ svol3 source=vol3 sourcedg=dbasedg
You can use the vxsnap snapwait command to wait for synchronization of the linked snapshot volume to complete:
# vxsnap -g volumedg snapwait volume mirvol=snapvol
Repeat step 5 through step 15 each time that you need to back up the volume.