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
Configuring the response to I/O failures
You can configure how DMP responds to failed I/O requests on the paths to a specified enclosure, disk array name, or type of array. By default, DMP is configured to retry a failed I/O request up to five times for a single path.
To display the current settings for handling I/O request failures that are applied to the paths to an enclosure, array name or array type, use the vxdmpadm getattr command.
To set a limit for the number of times that DMP attempts to retry sending an I/O request on a path, use the following command:
# vxdmpadm setattr \ {enclosure enc-name|arrayname name|arraytype type} \ recoveryoption=fixedretry retrycount=n
The value of the argument to retrycount specifies the number of retries to be attempted before DMP reschedules the I/O request on another available path, or fails the request altogether.
As an alternative to specifying a fixed number of retries, you can specify the amount of time DMP allows for handling an I/O request. If the I/O request does not succeed within that time, DMP fails the I/O request. To specify an iotimeout value, use the following command:
# vxdmpadm setattr \ {enclosure enc-name|arrayname name|arraytype type} \ recoveryoption=timebound iotimeout=seconds
The default value of iotimeout is 300 seconds. For some applications such as Oracle, it may be desirable to set iotimeout to a larger value. The iotimeout value for DMP should be greater than the I/O service time of the underlying operating system layers.
Note:
The fixedretry and timebound settings are mutually exclusive.
The following example configures time-bound recovery for the enclosure enc0, and sets the value of iotimeout to 360 seconds:
# vxdmpadm setattr enclosure enc0 recoveryoption=timebound \ iotimeout=360
The next example sets a fixed-retry limit of 10 for the paths to all Active/Active arrays:
# vxdmpadm setattr arraytype A/A recoveryoption=fixedretry \ retrycount=10
Specifying recoveryoption=default resets DMP to the default settings corresponding to recoveryoption=fixedretry retrycount=5, for example:
# vxdmpadm setattr arraytype A/A recoveryoption=default
The above command also has the effect of configuring I/O throttling with the default settings.
Note:
The response to I/O failure settings is persistent across reboots of the system.