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
FastResync limitations
The following limitations apply to FastResync:
Persistent FastResync is supported for RAID-5 volumes, but this prevents the use of the relayout or resize operations on the volume while a DCO is associated with it.
Neither non-persistent nor persistent FastResync can be used to resynchronize mirrors after a system crash. Dirty region logging (DRL), which can coexist with FastResync, should be used for this purpose. In VxVM 4.0 and later releases, DRL logs may be stored in a version 20 DCO volume.
When a subdisk is relocated, the entire plex is marked "dirty" and a full resynchronization becomes necessary.
If a snapshot volume is split off into another disk group, non-persistent FastResync cannot be used to resynchronize the snapshot plexes with the original volume when the disk group is rejoined with the original volume's disk group. Persistent FastResync must be used for this purpose.
If you move or split an original volume (on which persistent FastResync is enabled) into another disk group, and then move or join it to a snapshot volume's disk group, you cannot use vxassist snapback to resynchronize traditional snapshot plexes with the original volume. This restriction arises because a snapshot volume references the original volume by its record ID at the time that the snapshot volume was created. Moving the original volume to a different disk group changes the volume's record ID, and so breaks the association. However, in such a case, you can use the vxplex snapback command with the -f (force) option to perform the snapback.
Note:
This restriction only applies to traditional snapshots. It does not apply to instant snapshots.
Any operation that changes the layout of a replica volume can mark the FastResync change map for that snapshot "dirty" and require a full resynchronization during snapback. Operations that cause this include subdisk split, subdisk move, and online relayout of the replica. It is safe to perform these operations after the snapshot is completed.
See the vxassist (1M) manual page.
See the vxplex (1M) manual page.
See the vxvol (1M) manual page.