Veritas™ Volume Manager Administrator's Guide

Last Published:
Product(s): InfoScale & Storage Foundation (5.1 SP1)
Platform: HP-UX
  1. Understanding Veritas Volume Manager
    1.  
      About Veritas Volume Manager
    2. VxVM and the operating system
      1.  
        How data is stored
    3. How VxVM handles storage management
      1. Physical objects
        1.  
          Disk arrays
        2.  
          Multiple paths to disk arrays
        3.  
          Device discovery
        4.  
          About enclosure-based naming
      2. Virtual objects
        1.  
          Combining virtual objects in VxVM
        2.  
          Disk groups
        3.  
          VM disks
        4.  
          Subdisks
        5.  
          Plexes
        6.  
          Volumes
    4. Volume layouts in VxVM
      1.  
        Non-layered volumes
      2.  
        Layered volumes
      3.  
        Layout methods
      4.  
        Concatenation, spanning, and carving
      5.  
        Striping (RAID-0)
      6.  
        Mirroring (RAID-1)
      7.  
        Striping plus mirroring (mirrored-stripe or RAID-0+1)
      8.  
        Mirroring plus striping (striped-mirror, RAID-1+0 or RAID-10)
      9. RAID-5 (striping with parity)
        1.  
          Traditional RAID-5 arrays
        2.  
          Veritas Volume Manager RAID-5 arrays
        3.  
          Left-symmetric layout
        4.  
          RAID-5 logging
        5.  
          Layered volumes
    5. Online relayout
      1.  
        How online relayout works
      2.  
        Limitations of online relayout
      3.  
        Transformation characteristics
      4.  
        Transformations and volume length
    6. Volume resynchronization
      1.  
        Dirty flags
      2.  
        Resynchronization process
    7. Dirty region logging
      1.  
        Log subdisks and plexes
      2.  
        Sequential DRL
    8. Volume snapshots
      1.  
        Comparison of snapshot features
    9. FastResync
      1.  
        FastResync enhancements
      2. Non-persistent FastResync
        1.  
          How non-persistent FastResync works with snapshots
      3.  
        Persistent FastResync
      4. DCO volume versioning
        1.  
          Version 0 DCO volume layout
        2.  
          Version 20 DCO volume layout
        3.  
          How persistent FastResync works with snapshots
        4.  
          Effect of growing a volume on the FastResync map
      5.  
        FastResync limitations
    10.  
      Hot-relocation
    11.  
      Volume sets
  2. Provisioning new usable storage
    1.  
      Provisioning new usable storage
    2.  
      Growing the existing storage by adding a new LUN
    3.  
      Growing the existing storage by growing the LUN
  3. Administering disks
    1.  
      About disk management
    2. Disk devices
      1. Disk device naming in VxVM
        1.  
          Operating system-based naming
        2.  
          Enclosure-based naming
      2.  
        Private and public disk regions
    3. Discovering and configuring newly added disk devices
      1.  
        Partial device discovery
      2. Discovering disks and dynamically adding disk arrays
        1.  
          How DMP claims devices
        2.  
          Disk categories
        3.  
          Adding support for a new disk array
        4.  
          Enabling discovery of new disk arrays
      3.  
        Third-party driver coexistence
      4. How to administer the Device Discovery Layer
        1.  
          Listing all the devices including iSCSI
        2.  
          Listing all the Host Bus Adapters including iSCSI
        3.  
          Listing the ports configured on a Host Bus Adapter
        4.  
          Listing the targets configured from a Host Bus Adapter or a port
        5.  
          Listing the devices configured from a Host Bus Adapter and target
        6.  
          Getting or setting the iSCSI operational parameters
        7.  
          Listing all supported disk arrays
        8.  
          Excluding support for a disk array library
        9.  
          Re-including support for an excluded disk array library
        10.  
          Listing excluded disk arrays
        11.  
          Listing supported disks in the DISKS category
        12.  
          Displaying details about a supported array library
        13.  
          Adding unsupported disk arrays to the DISKS category
        14.  
          Removing disks from the DISKS category
        15.  
          Foreign devices
    4.  
      Disks under VxVM control
    5. Changing the disk-naming scheme
      1.  
        Examples of using vxddladm to change the naming scheme
      2.  
        Displaying the disk-naming scheme
      3.  
        Regenerating persistent device names
      4.  
        Changing device naming for TPD-controlled enclosures
      5. Persistent simple or nopriv disks with enclosure-based naming
        1.  
          Removing the error state for persistent simple or nopriv disks in the boot disk group
        2.  
          Removing the error state for persistent simple or nopriv disks in non-boot disk groups
    6.  
      About the Array Volume Identifier (AVID) attribute
    7.  
      Discovering the association between enclosure-based disk names and OS-based disk names
    8.  
      About disk installation and formatting
    9.  
      Displaying or changing default disk layout attributes
    10. Adding a disk to VxVM
      1.  
        Disk reinitialization
      2.  
        Using vxdiskadd to put a disk under VxVM control
    11.  
      RAM disk support in VxVM
    12.  
      Veritas Volume Manager co-existence with Oracle Automatic Storage Management (ASM) disks
    13. Rootability
      1.  
        VxVM root disk volume restrictions
      2.  
        Root disk mirrors
      3.  
        Booting root volumes
      4.  
        Setting up a VxVM root disk and mirror
      5.  
        Creating an LVM root disk from a VxVM root disk
      6.  
        Adding swap volumes to a VxVM rootable system
      7.  
        Adding persistent dump volumes to a VxVM rootable system
      8.  
        Removing a persistent dump volume
    14. Displaying disk information
      1.  
        Displaying disk information with vxdiskadm
    15.  
      Controlling Powerfail Timeout
    16. Removing disks
      1.  
        Removing a disk with subdisks
      2.  
        Removing a disk with no subdisks
    17.  
      Removing a disk from VxVM control
    18. Removing and replacing disks
      1.  
        Replacing a failed or removed disk
    19.  
      Enabling a disk
    20.  
      Taking a disk offline
    21.  
      Renaming a disk
    22.  
      Reserving disks
  4. Administering Dynamic Multi-Pathing
    1. How DMP works
      1. How DMP monitors I/O on paths
        1.  
          Path failover mechanism
        2.  
          Subpaths Failover Group (SFG)
        3.  
          Low Impact Path Probing (LIPP)
        4.  
          I/O throttling
      2.  
        Load balancing
      3. DMP coexistence with HP-UX native multi-pathing
        1.  
          Migrating between DMP and HP-UX native multi-pathing
      4. DMP in a clustered environment
        1.  
          About enabling or disabling controllers with shared disk groups
    2.  
      Disabling multi-pathing and making devices invisible to VxVM
    3.  
      Enabling multi-pathing and making devices visible to VxVM
    4.  
      About enabling and disabling I/O for controllers and storage processors
    5.  
      About displaying DMP database information
    6.  
      Displaying the paths to a disk
    7.  
      Setting customized names for DMP nodes
    8. Administering DMP using vxdmpadm
      1.  
        Retrieving information about a DMP node
      2.  
        Displaying consolidated information about the DMP nodes
      3.  
        Displaying the members of a LUN group
      4.  
        Displaying paths controlled by a DMP node, controller, enclosure, or array port
      5.  
        Displaying information about controllers
      6.  
        Displaying information about enclosures
      7.  
        Displaying information about array ports
      8.  
        Displaying extended device attributes
      9.  
        Suppressing or including devices for VxVM or DMP control
      10. Gathering and displaying I/O statistics
        1.  
          Examples of using the vxdmpadm iostat command
        2.  
          Displaying statistics for queued or erroneous I/Os
        3.  
          Displaying cumulative I/O statistics
      11.  
        Setting the attributes of the paths to an enclosure
      12.  
        Displaying the redundancy level of a device or enclosure
      13.  
        Specifying the minimum number of active paths
      14.  
        Displaying the I/O policy
      15. Specifying the I/O policy
        1.  
          Scheduling I/O on the paths of an Asymmetric Active/Active array
        2.  
          Example of applying load balancing in a SAN
      16.  
        Disabling I/O for paths, controllers or array ports
      17.  
        Enabling I/O for paths, controllers or array ports
      18.  
        Renaming an enclosure
      19.  
        Configuring the response to I/O failures
      20.  
        Configuring the I/O throttling mechanism
      21.  
        Configuring Subpaths Failover Groups (SFG)
      22.  
        Configuring Low Impact Path Probing
      23.  
        Displaying recovery option values
      24.  
        Configuring DMP path restoration policies
      25.  
        Stopping the DMP path restoration thread
      26.  
        Displaying the status of the DMP path restoration thread
      27.  
        Displaying information about the DMP error-handling thread
      28.  
        Configuring array policy modules
  5. Online dynamic reconfiguration
    1.  
      About online dynamic reconfiguration
    2. Reconfiguring a LUN online that is under DMP control
      1.  
        Removing LUNs dynamically from an existing target ID
      2.  
        Adding new LUNs dynamically to a new target ID
      3.  
        About detecting target ID reuse if the operating system device tree is not cleaned up
      4.  
        Scanning an operating system device tree after adding or removing LUNs
      5.  
        Cleaning up the operating system device tree after removing LUNs
    3.  
      Upgrading the array controller firmware online
    4.  
      Replacing a host bus adapter
  6. Creating and administering disk groups
    1. About disk groups
      1.  
        Specification of disk groups to commands
      2.  
        System-wide reserved disk groups
      3. Rules for determining the default disk group
        1.  
          Displaying the system-wide boot disk group
        2.  
          Displaying and specifying the system-wide default disk group
      4.  
        Disk group versions
    2. Displaying disk group information
      1.  
        Displaying free space in a disk group
    3. Creating a disk group
      1.  
        Creating a disk group with an earlier disk group version
    4.  
      Adding a disk to a disk group
    5.  
      Removing a disk from a disk group
    6.  
      Moving disks between disk groups
    7.  
      Deporting a disk group
    8. Importing a disk group
      1.  
        Setting the automatic recovery of volumes
    9.  
      Handling of minor number conflicts
    10. Moving disk groups between systems
      1.  
        Handling errors when importing disks
      2.  
        Reserving minor numbers for disk groups
      3.  
        Compatibility of disk groups between platforms
    11. Handling cloned disks with duplicated identifiers
      1.  
        Writing a new UDID to a disk
      2.  
        Importing a disk group containing cloned disks
      3. Sample cases of operations on cloned disks
        1.  
          Enabling configuration database copies on tagged disks
        2.  
          Importing cloned disks without tags
        3.  
          Importing cloned disks with tags
      4.  
        Considerations when using EMC CLARiiON SNAPSHOT LUNs
    12.  
      Renaming a disk group
    13. Handling conflicting configuration copies
      1.  
        Example of a serial split brain condition in a cluster
      2.  
        Correcting conflicting configuration information
    14. Reorganizing the contents of disk groups
      1.  
        Limitations of disk group split and join
      2. Listing objects potentially affected by a move
        1.  
          Moving DCO volumes between disk groups
      3.  
        Moving objects between disk groups
      4.  
        Splitting disk groups
      5.  
        Joining disk groups
    15.  
      Disabling a disk group
    16. Destroying a disk group
      1.  
        Recovering a destroyed disk group
    17.  
      Upgrading the disk group version
    18.  
      About the configuration daemon in VxVM
    19.  
      Backing up and restoring disk group configuration data
    20.  
      Using vxnotify to monitor configuration changes
    21.  
      Working with existing ISP disk groups
  7. Creating and administering subdisks and plexes
    1.  
      About subdisks
    2.  
      Creating subdisks
    3.  
      Displaying subdisk information
    4.  
      Moving subdisks
    5.  
      Splitting subdisks
    6.  
      Joining subdisks
    7.  
      Associating subdisks with plexes
    8.  
      Associating log subdisks
    9.  
      Dissociating subdisks from plexes
    10.  
      Removing subdisks
    11.  
      Changing subdisk attributes
    12.  
      About plexes
    13.  
      Creating plexes
    14.  
      Creating a striped plex
    15. Displaying plex information
      1.  
        Plex states
      2.  
        Plex condition flags
      3.  
        Plex kernel states
    16.  
      Attaching and associating plexes
    17.  
      Taking plexes offline
    18.  
      Detaching plexes
    19. Reattaching plexes
      1.  
        Automatic plex reattachment
    20.  
      Moving plexes
    21.  
      Copying volumes to plexes
    22.  
      Dissociating and removing plexes
    23.  
      Changing plex attributes
  8. Creating volumes
    1.  
      About volume creation
    2. Types of volume layouts
      1.  
        Supported volume logs and maps
    3. Creating a volume
      1.  
        Advanced approach
      2.  
        Assisted approach
    4. Using vxassist
      1.  
        Setting default values for vxassist
      2.  
        Using the SmartMove™ feature while attaching a plex
    5.  
      Discovering the maximum size of a volume
    6.  
      Disk group alignment constraints on volumes
    7.  
      Creating a volume on any disk
    8. Creating a volume on specific disks
      1.  
        Creating a volume on SSD devices
      2.  
        Specifying ordered allocation of storage to volumes
    9. Creating a mirrored volume
      1.  
        Creating a mirrored-concatenated volume
      2.  
        Creating a concatenated-mirror volume
    10.  
      Creating a volume with a version 0 DCO volume
    11.  
      Creating a volume with a version 20 DCO volume
    12.  
      Creating a volume with dirty region logging enabled
    13. Creating a striped volume
      1.  
        Creating a mirrored-stripe volume
      2.  
        Creating a striped-mirror volume
    14.  
      Mirroring across targets, controllers or enclosures
    15.  
      Mirroring across media types (SSD and HDD)
    16.  
      Creating a RAID-5 volume
    17.  
      Creating tagged volumes
    18. Creating a volume using vxmake
      1.  
        Creating a volume using a vxmake description file
    19. Initializing and starting a volume
      1.  
        Initializing and starting a volume created using vxmake
    20.  
      Accessing a volume
    21. Using rules and persistent attributes to make volume allocation more efficient
      1.  
        Understanding persistent attributes
      2.  
        Rule file format
      3.  
        Using rules to create a volume
      4.  
        Using persistent attributes
  9. Administering volumes
    1.  
      About volume administration
    2. Displaying volume information
      1.  
        Volume states
      2.  
        Volume kernel states
    3. Monitoring and controlling tasks
      1.  
        Specifying task tags
      2. Managing tasks with vxtask
        1.  
          vxtask operations
        2.  
          Using the vxtask command
    4.  
      About SF Thin Reclamation feature
    5. Reclamation of storage on thin reclamation arrays
      1.  
        Identifying thin and thin reclamation LUNs
      2.  
        How reclamation on a deleted volume works
      3.  
        Thin Reclamation of a disk, a disk group, or an enclosure
      4.  
        Thin Reclamation of a file system
      5.  
        Triggering space reclamation
    6.  
      Monitoring Thin Reclamation using the vxtask command
    7.  
      Using SmartMove with Thin Provisioning
    8.  
      Admin operations on an unmounted VxFS thin volume
    9. Stopping a volume
      1.  
        Putting a volume in maintenance mode
    10.  
      Starting a volume
    11. Resizing a volume
      1.  
        Resizing volumes with vxresize
      2. Resizing volumes with vxassist
        1.  
          Extending to a given length
        2.  
          Extending by a given length
        3.  
          Shrinking to a given length
        4.  
          Shrinking by a given length
      3.  
        Resizing volumes with vxvol
    12. Adding a mirror to a volume
      1.  
        Mirroring all volumes
      2.  
        Mirroring volumes on a VM disk
    13.  
      Removing a mirror
    14.  
      Adding logs and maps to volumes
    15. Preparing a volume for DRL and instant snapshots
      1.  
        Specifying storage for version 20 DCO plexes
      2.  
        Using a DCO and DCO volume with a RAID-5 volume
      3.  
        Determining the DCO version number
      4.  
        Determining if DRL is enabled on a volume
      5.  
        Determining if DRL logging is active on a volume
      6.  
        Disabling and re-enabling DRL
      7.  
        Removing support for DRL and instant snapshots from a volume
    16. Adding traditional DRL logging to a mirrored volume
      1.  
        Removing a traditional DRL log
    17.  
      Upgrading existing volumes to use version 20 DCOs
    18.  
      Setting tags on volumes
    19.  
      Changing the read policy for mirrored volumes
    20.  
      Removing a volume
    21.  
      Moving volumes from a VM disk
    22. Enabling FastResync on a volume
      1.  
        Checking whether FastResync is enabled on a volume
      2.  
        Disabling FastResync
    23. Performing online relayout
      1.  
        Permitted relayout transformations
      2.  
        Specifying a non-default layout
      3.  
        Specifying a plex for relayout
      4.  
        Tagging a relayout operation
      5.  
        Viewing the status of a relayout
      6.  
        Controlling the progress of a relayout
    24.  
      Converting between layered and non-layered volumes
    25. Adding a RAID-5 log
      1.  
        Adding a RAID-5 log using vxplex
      2.  
        Removing a RAID-5 log
  10. Creating and administering volume sets
    1.  
      About volume sets
    2.  
      Creating a volume set
    3.  
      Adding a volume to a volume set
    4.  
      Removing a volume from a volume set
    5.  
      Listing details of volume sets
    6.  
      Stopping and starting volume sets
    7. Raw device node access to component volumes
      1.  
        Enabling raw device access when creating a volume set
      2.  
        Displaying the raw device access settings for a volume set
      3.  
        Controlling raw device access for an existing volume set
  11. Configuring off-host processing
    1.  
      About off-host processing solutions
    2. Implemention of off-host processing solutions
      1.  
        Implementing off-host online backup
      2.  
        Implementing decision support
  12. Administering hot-relocation
    1.  
      About hot-relocation
    2. How hot-relocation works
      1.  
        Partial disk failure mail messages
      2.  
        Complete disk failure mail messages
      3.  
        How space is chosen for relocation
    3.  
      Configuring a system for hot-relocation
    4.  
      Displaying spare disk information
    5.  
      Marking a disk as a hot-relocation spare
    6.  
      Removing a disk from use as a hot-relocation spare
    7.  
      Excluding a disk from hot-relocation use
    8.  
      Making a disk available for hot-relocation use
    9.  
      Configuring hot-relocation to use only spare disks
    10. Moving relocated subdisks
      1.  
        Moving relocated subdisks using vxdiskadm
      2.  
        Moving relocated subdisks using vxassist
      3. Moving relocated subdisks using vxunreloc
        1.  
          Moving hot-relocated subdisks back to their original disk
        2.  
          Moving hot-relocated subdisks back to a different disk
        3.  
          Forcing hot-relocated subdisks to accept different offsets
        4.  
          Examining which subdisks were hot-relocated from a disk
      4.  
        Restarting vxunreloc after errors
    11.  
      Modifying the behavior of hot-relocation
  13. Administering cluster functionality (CVM)
    1. Overview of clustering
      1.  
        Overview of cluster volume management
      2.  
        Private and shared disk groups
      3.  
        Activation modes of shared disk groups
      4. Connectivity policy of shared disk groups
        1.  
          Global detach policy
        2.  
          Local detach policy
        3.  
          Guidelines for choosing detach policies
        4.  
          Disk group failure policy
        5.  
          Guidelines for failure policies
      5.  
        Effect of disk connectivity on cluster reconfiguration
      6.  
        Limitations of shared disk groups
    2. Multiple host failover configurations
      1.  
        Import lock
      2.  
        Failover
      3.  
        Corruption of disk group configuration
    3.  
      About the cluster functionality of VxVM
    4. CVM initialization and configuration
      1. Cluster reconfiguration
        1.  
          vxclustadm utility
      2. Volume reconfiguration
        1.  
          vxconfigd daemon
        2.  
          vxconfigd daemon recovery
      3.  
        Node shutdown
      4.  
        Cluster shutdown
    5. Dirty region logging in cluster environments
      1.  
        How DRL works in a cluster environment
    6. Administering VxVM in cluster environments
      1.  
        Requesting node status and discovering the master node
      2. Changing the CVM master manually
        1.  
          Errors during CVM master switching
      3.  
        Determining if a LUN is in a shareable disk group
      4.  
        Listing shared disk groups
      5.  
        Creating a shared disk group
      6. Importing disk groups as shared
        1.  
          Forcibly importing a disk group
      7.  
        Handling cloned disks in a shared disk group
      8.  
        Converting a disk group from shared to private
      9.  
        Moving objects between shared disk groups
      10.  
        Splitting shared disk groups
      11.  
        Joining shared disk groups
      12.  
        Changing the activation mode on a shared disk group
      13.  
        Setting the disk detach policy on a shared disk group
      14.  
        Setting the disk group failure policy on a shared disk group
      15.  
        Creating volumes with exclusive open access by a node
      16.  
        Setting exclusive open access to a volume by a node
      17.  
        Displaying the cluster protocol version
      18.  
        Displaying the supported cluster protocol version range
      19.  
        Recovering volumes in shared disk groups
      20.  
        Obtaining cluster performance statistics
      21.  
        Administering CVM from the slave node
  14. Administering sites and remote mirrors
    1. About sites and remote mirrors
      1.  
        About site-based allocation
      2.  
        About site consistency
      3.  
        About site tags
      4.  
        About the site read policy
    2.  
      Making an existing disk group site consistent
    3.  
      Configuring a new disk group as a Remote Mirror configuration
    4. Fire drill - testing the configuration
      1.  
        Simulating site failure
      2.  
        Verifying the secondary site
      3.  
        Recovery from simulated site failure
    5. Changing the site name
      1.  
        Resetting the site name for a host
    6. Administering the Remote Mirror configuration
      1.  
        Configuring site tagging for disks or enclosures
      2.  
        Configuring automatic site tagging for a disk group
      3.  
        Configuring site consistency on a volume
    7.  
      Examples of storage allocation by specifying sites
    8.  
      Displaying site information
    9. Failure and recovery scenarios
      1.  
        Recovering from a loss of site connectivity
      2.  
        Recovering from host failure
      3.  
        Recovering from storage failure
      4.  
        Recovering from site failure
      5.  
        Automatic site reattachment
  15. Performance monitoring and tuning
    1. Performance guidelines
      1.  
        Data assignment
      2.  
        Striping
      3.  
        Mirroring
      4.  
        Combining mirroring and striping
    2. RAID-5
      1.  
        Volume read policies
    3. Performance monitoring
      1.  
        Setting performance priorities
      2. Obtaining performance data
        1.  
          Tracing volume operations
        2.  
          Printing volume statistics
      3. Using performance data
        1.  
          Using I/O statistics
        2.  
          Using I/O tracing
    4. Tuning VxVM
      1.  
        General tuning guidelines
      2. Tuning guidelines for large systems
        1.  
          Number of configuration copies for a disk group
      3.  
        Changing the values of VxVM tunables
      4.  
        Tunable parameters for VxVM
      5.  
        DMP tunable parameters
      6.  
        Disabling I/O statistics collection
      7.  
        Enabling I/O statistics collection
  16. Appendix A. Using Veritas Volume Manager commands
    1.  
      About Veritas Volume Manager commands
    2.  
      CVM commands supported for executing on the slave node
    3. Online manual pages
      1.  
        Section 1M - administrative commands
      2.  
        Section 4 - file formats
      3.  
        Section 7 - device driver interfaces
  17. Appendix B. Configuring Veritas Volume Manager
    1.  
      Setup tasks after installation
    2.  
      Unsupported disk arrays
    3.  
      Foreign devices
    4.  
      Initialization of disks and creation of disk groups
    5. Guidelines for configuring storage
      1.  
        Mirroring guidelines
      2.  
        Dirty region logging guidelines
      3.  
        Striping guidelines
      4.  
        RAID-5 guidelines
      5.  
        Hot-relocation guidelines
      6.  
        Accessing volume devices
    6.  
      VxVM's view of multipathed devices
    7. Cluster support
      1.  
        Configuring shared disk groups
      2.  
        Converting existing VxVM disk groups to shared disk groups
  18.  
    Glossary

DMP tunable parameters

Table: DMP parameters that are tunable shows the DMP parameters that can be tuned by using the vxdmpadm settune command.

Table: DMP parameters that are tunable

Parameter

Description

dmp_cache_open

If this parameter is set to on, the first open of a device that is performed by an array support library (ASL) is cached. This caching enhances the performance of device discovery by minimizing the overhead that is caused by subsequent opens by ASLs. If this parameter is set to off, caching is not performed.

The default value is on.

dmp_daemon_count

The number of kernel threads that are available for servicing path error handling, path restoration, and other DMP administrative tasks.

The default number of threads is 10.

dmp_delayq_interval

How long DMP should wait before retrying I/O after an array fails over to a standby path. Some disk arrays are not capable of accepting I/O requests immediately after failover.

The default value is 15 seconds.

dmp_enable_restore

If this parameter is set to on, it enables the path restoration thread to be started.

See Configuring DMP path restoration policies.

If this parameter is set to off, it disables the path restoration thread. If the path restoration thread is currently running, use the vxdmpadm stop restore command to stop the thread.

The default is on.

See Stopping the DMP path restoration thread.

dmp_evm_handling

Determines whether DMP listens to disk-related events from the Event Monitoring framework (EVM) on HP-UX.

The default is on.

If this parameter is set to on, DMP listens and reacts to events from EVM.

If the parameter is set to off, DMP stops listening and reacting to events.

dmp_fast_recovery

Whether DMP should try to obtain SCSI error information directly from the HBA interface. Setting the value to on can potentially provide faster error recovery, provided that the HBA interface supports the error enquiry feature. If this parameter is set to off, the HBA interface is not used.

The default setting is off.

dmp_health_time

DMP detects intermittently failing paths, and prevents I/O requests from being sent on them. The value of dmp_health_time represents the time in seconds for which a path must stay healthy. If a path's state changes back from enabled to disabled within this time period, DMP marks the path as intermittently failing, and does not re-enable the path for I/O until dmp_path_age seconds elapse.

The default value is 60 seconds.

A value of 0 prevents DMP from detecting intermittently failing paths.

dmp_log_level

The level of detail that is displayed for DMP console messages. The following level values are defined:

1 - Displays all DMP log messages that existed in releases before 5.0.

2 - Displays level 1 messages plus messages that relate to path or disk addition or removal, SCSI errors, IO errors and DMP node migration.

3 - Displays level 1 and 2 messages plus messages that relate to path throttling, suspect path, idle path and insane path logic.

4 - Displays level 1, 2 and 3 messages plus messages that relate to setting or changing attributes on a path and tunable related changes.

The default value is 1.

dmp_low_impact_probe

Determines if the path probing by restore daemon is optimized or not. Set it to on to enable optimization and off to disable. Path probing is optimized only when restore policy is check_disabled or during check_disabled phase of check_periodic policy.

The default value is on.

dmp_lun_retry_timeout

Retry period for handling transient errors. The value is specified in seconds.

When all paths to a disk fail, there may be certain paths that have a temporary failure and are likely to be restored soon. The I/Os may be failed to the application layer even though the failures are transient, unless the I/Os are retried. The dmp_lun_retry_timeout tunable provides a mechanism to retry such transient errors.

If the tunable is set to a non-zero value, I/Os to a disk with all failed paths are retried until dmp_lun_retry_timeout interval or until the I/O succeeds on one of the path, whichever happens first.

The default value of tunable is 0, which means that the paths are probed only once.

dmp_monitor_fabric

Determines whether the Event Source daemon (vxesd) uses the Storage Networking Industry Association (SNIA) HBA API. This API allows DDL to improve the performance of failover by collecting information about the SAN topology and by monitoring fabric events.

If this parameter is set to on, DDL uses the SNIA HBA API. (Note that the HBA vendor specific HBA-API library should be available to use this feature.)

If this parameter is set to off, the SNIA HBA API is not used.

The default setting is off for releases before 5.0 that have been patched to support this DDL feature. The default setting is on for 5.0 and later releases.

dmp_monitor_osevent

Determines whether the Event Source daemon (vxesd) monitors operating system events such as reconfiguration operations.

If this parameter is set to on, vxesd monitors operations such as attaching operating system devices.

If this parameter is set to off, vxesd does not monitor operating system operations. When DMP co-exists with EMC PowerPath, Symantec recommends setting this parameter to off to avoid any issues.

The default setting is on, unless EMC PowerPath is installed. If you install DMP on a system that already has PowerPath installed, DMP sets the dmp_monitor_osevent to off.

dmp_native_support

Determines whether DMP will do multi-pathing for native devices.

Set the tunable to on to have DMP do multi-pathing for native devices.

When a Storage Foundation product is installed, the default value is off.

When Veritas Dynamic Multi-Pathing is installed, the default value is on.

dmp_path_age

The time for which an intermittently failing path needs to be monitored as healthy before DMP again tries to schedule I/O requests on it.

The default value is 300 seconds.

A value of 0 prevents DMP from detecting intermittently failing paths.

dmp_pathswitch_blks_shift

The default number of contiguous I/O blocks that are sent along a DMP path to an array before switching to the next available path. The value is expressed as the integer exponent of a power of 2; for example 9 represents 512 blocks.

The default value of this parameter is set to 9. In this case, 1024 blocks (1MB) of contiguous I/O are sent over a DMP path before switching. For intelligent disk arrays with internal data caches, better throughput may be obtained by increasing the value of this tunable. For example, for the HDS 9960 A/A array, the optimal value is between 14 and 16 for an I/O activity pattern that consists mostly of sequential reads or writes.

This parameter only affects the behavior of the balanced I/O policy. A value of 0 disables multi-pathing for the policy unless the vxdmpadm command is used to specify a different partition size for an array.

dmp_probe_idle_lun

If DMP statistics gathering is enabled, set this tunable to on (default) to have the DMP path restoration thread probe idle LUNs. Set this tunable to off to turn off this feature. (Idle LUNs are VM disks on which no I/O requests are scheduled.) The value of this tunable is only interpreted when DMP statistics gathering is enabled. Turning off statistics gathering also disables idle LUN probing.

The default value is on.

dmp_probe_threshold

If the dmp_low_impact_probe is turned on, dmp_probe_threshold determines the number of paths to probe before deciding on changing the state of other paths in the same subpath failover group.

The default value is 5.

dmp_queue_depth

The maximum number of queued I/O requests on a path during I/O throttling.

The default value is 40.

A value can also be set for paths to individual arrays by using the vxdmpadm command.

dmp_restore_cycles

If the DMP restore policy is check_periodic, the number of cycles after which the check_all policy is called.

The default value is 10.

The value of this tunable can also be set using the vxdmpadm start restore command.

See Configuring DMP path restoration policies.

dmp_restore_interval

The interval attribute specifies how often the path restoration thread examines the paths. Specify the time in seconds.

The default value is 300.

The value of this tunable can also be set using the vxdmpadm start restore command.

See Configuring DMP path restoration policies.

dmp_restore_policy

The DMP restore policy, which can be set to one of the following values:

  • check_all

  • check_alternate

  • check_disabled

  • check_periodic

The default value is check_disabled.

The value of this tunable can also be set using the vxdmpadm start restore command.

See Configuring DMP path restoration policies.

dmp_retry_count

If an inquiry succeeds on a path, but there is an I/O error, the number of retries to attempt on the path.

The default value is 5.

A value can also be set for paths to individual arrays by using the vxdmpadm command.

dmp_scsi_timeout

Determines the timeout value to be set for any SCSI command that is sent via DMP. If the HBA does not receive a response for a SCSI command that it has sent to the device within the timeout period, the SCSI command is returned with a failure error code.

The default value is 60 seconds.

dmp_sfg_threshold

Determines the minimum number of paths that should be failed in a failover group before DMP starts suspecting other paths in the same failover group. The value of 0 disables the failover logic based on subpath failover groups.

The default value is 1.

dmp_stat_interval

The time interval between gathering DMP statistics.

The default and minimum value are 1 second.

More Information

Specifying the I/O policy

Configuring the I/O throttling mechanism

Configuring the response to I/O failures