How DMP works | HP Veritas Volume Manager 5.0 -UX 11i v3 guide

Chapter

Administering dynamic multipathing (DMP)

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The dynamic multipathing (DMP) feature of Veritas Volume Manager (VxVM) provides greater availability, reliability and performance by using path failover and load balancing. This feature is available for multiported disk arrays from various vendors.

DMP coexists with the native multipathing in HP-UX. For more information, see “DMP coexistence with HP-UX native multipathing” on page 130.

How DMP works

Multiported disk arrays can be connected to host systems through multiple paths. To detect the various paths to a disk, DMP uses a mechanism that is specific to each supported array type. DMP can also differentiate between different enclosures of a supported array type that are connected to the same host system.

See “Discovering and configuring newly added disk devices” on page 82 for a description of how to make newly added disk hardware known to a host system.

The multipathing policy used by DMP depends on the characteristics of the disk array:

■An Active/Passive array (A/P array) allows access to its LUNs (logical units; real disks or virtual disks created using hardware) via the primary (active) path on a single controller (also known as an access port or a storage processor) during normal operation.

In implicit failover mode (or autotrespass mode), an A/P array automatically fails over by scheduling I/O to the secondary (passive) path on a separate controller if the primary path fails. This passive port is not used for I/O until the active port fails. In A/P arrays, path failover can occur for a single LUN if I/O fails on the primary path.

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HP Veritas Volume Manager 5.0 -UX 11i v3 manual Administering dynamic multipathing DMP, How DMP works

Contents

Veritas Volume Manager Administrator’s Guide Legal Notices Page Contents Using vxdiskadd to place a disk under control of VxVM VxVM root disk volume restrictionsBooting root volumes Setting up a VxVM root disk and mirror Taking a disk offline 118 119133 136 185 167207 Setting default values for vxassist 241 215Displaying subdisk information 216 217 274 252275 Moving volumes from a VM disk 290 288289 290 Chapter Creating and administering volume sets 356 386 387388 390 434 441 Setup tasks after installation 511 463507 512 521 531 Understanding Veritas Volume Manager Veritas Enterprise Administrator User’s Guide VxVM and the operating system How data is stored How VxVM handles storage management Physical objects-physical disks Disk arrays Device discovery Multipathed disk arraysOperating system Enclosure-based naming Fibre Channel hub or switch Provide redundant loop access C2t99d0 Combining virtual objects in VxVM Virtual objectsVirtual objects in VxVM include the following Connection between objects in VxVM Disk groups VM disks Subdisks Plexes Volumes How VxVM handles storage management Disk01-01 vol06-01 Implementation of non-layered volumes Volume layouts in VxVMImplementation of layered volumes Concatenation and spanning Layout methodsFollowing sections describe each layout method 12 Example of concatenation Data Disk01-01 Example of spanning Data +1 n+2 Striping RAID-0 Su1 Su2 Su3 Devname3 Devname2 Mirroring RAID-1 Striping plus mirroring mirrored-stripe or RAID-0+1 17 Mirrored-stripe volume laid out on six disks Mirroring plus striping striped-mirror, RAID-1+0 or RAID-10 Column Mirror Striped plex You need a full license to use this feature Mirror volumesRAID-5 striping with parity Data Parity Traditional RAID-5 arrays Veritas Volume Manager RAID-5 arrays 22 Veritas Volume Manager RAID-5 array Stripe Left-symmetric layout Understanding Veritas Volume Manager RAID-5 logging Layered volumes Example of a striped-mirror layered volume Understanding Veritas Volume Manager Online relayout How online relayout works Three columns of length 5L/3 Striped volume Limitations of online relayout Transformation characteristics Transformations and volume length Dirty flags Volume resynchronizationResynchronization process Dirty region logging Dirty region logs Log subdisks and plexes Sequential DRL SmartSync recovery accelerator Data volume configuration Volume snapshots Redo log volume configuration Original Space than original Volume Comparison of snapshot featuresUse on creation Requires less storage FastResync FastResync enhancements Non-persistent FastResync Persistent FastResync DCO volume versioningHow non-persistent FastResync works with snapshots Version 0 DCO volume layout Version 20 DCO volume layout Where the size of each map in bytes is How persistent FastResync works with snapshots DCO FastResync Effect of growing a volume on the FastResync map FastResync limitations Volume sets Hot-relocation Volume sets Administering disks Disk devices Operating system-based naming Disk device naming in VxVMThere are two different methods of naming disk devices # vxdisk path egrep diskname Private and public disk regions Configures disk access records for them automatically To boot the system.Typically, most disks on a system areConfigured as this disk type. However, it is not a suitable Format for boot, root or swap disks, for mirrors or Discovering and configuring newly added disk devices Following command scans for the devices c1t1d0 and c2t2d0Partial device discovery Next example discovers fabric devices Disk categories Discovering disks and dynamically adding disk arraysFor more information, see the vxdisk1M manual Third-party driver coexistence Adding support for a new disk arrayEnabling discovery of new devices Removing support for a disk array Administering the Device Discovery Layer Listing details of supported disk arrays# vxddladm listsupport all # vxddladm listsupport libname=libraryname.sl Re-including support for an excluded disk array library Excluding support for a disk array libraryListing excluded disk arrays Listing supported disks in the Disks category Adding unsupported disk arrays to the Disks category Length=serialnolength policy=ap # vxddladm addjbod vid=SEAGATE pid=ST318404LSUN18G# vxdmpadm listenclosure all # vxdisk list Adding foreign devices Removing disks from the Disks category# vxddladm rmjbod vid=SEAGATE Placing disks under VxVM control See Migrating between DMP and HP-UX native multipathing on Mode Format of output from VxVM command DefaultChanging the disk-naming scheme Legacy VxVM vxdmpadm Error V-5-1-10910 Invalid da-name # vxdmpadm getlungroup dmpnodename=disk25 Regenerating persistent device names Restart the VxVM configuration demonThis regenerates the persistent name database # vxdmpadm setattr enclosure enclosure tpdmode=nativepseudo Changing device naming for TPD-controlled enclosures# vxdmpadm getsubpaths dmpnodename=enclosure-basedname Persistent simple or nopriv disks in the boot disk group # vxconfigd -kr reset Persistent simple or nopriv disks in non-boot disk groups Installing and formatting disksRe-import the disk group using the following command Add or initialize disks Menu VolumeManager/Disk/AddDisks Displaying and changing default disk layout attributesAdding a disk to VxVM C3t0d0 c3t1d0 c3t2d0 c3t3d0 Continue operation? y,n,q,? default y y Use default disk names for the disks? y,n,q,? default yExclude disks from hot-relocation use? y,n,q,? default n n Add site tag to disks? y,n,q,? default n Continue with operation? y,n,q,? default y y Enter the desired format cdsdisk,hpdisk,q,? default cdsdiskEnter desired private region length privlen,q,? default Following disks Using vxdiskadd to place a disk under control of VxVM Add or initialize other disks? y,n,q,? default nReinitializing a disk Vxdiskadm then proceeds to add the disks Rootability VxVM root disk volume restrictions Root disk mirrors Setting up a VxVM root disk and mirror Booting root volumes# /etc/vx/bin/vxcplvmroot -b c0t4d0 # /etc/vx/bin/vxcplvmroot -R 30 -v -b c0t4d0 # /etc/vx/bin/vxcplvmroot -m c1t1d0 -R 30 -v -b c0t4d0 Creating an LVM root disk from a VxVM root disk Adding swap volumes to a VxVM rootable system Adding persistent dump volumes to a VxVM rootable systemView the changed swap configuration Display the initial crash dump configuration Removing a persistent dump volume You can now remove the volume if required# crashconf -ds /dev/vx/dsk/bootdg/dumpvol Dynamic LUN expansion 109 # vxvol -g diskgroup stop volume1 volume2 Removing disks Continue with operation? y,n,q,? default y Remove another disk? y,n,q,? default nRemoving a disk with subdisks VxVM Info V-5-2-268 Removal of disk mydg01 is complete # /usr/lib/vxvm/bin/vxdiskunsetup c#t#d# Removing a disk from VxVM controlRemoving and replacing disks Removing a disk with no subdisks To replace a disk Are you sure you want do this? y,n,q,? default n# vxassist move mkting !mydg02 Following devices are available as replacements c0t1d0 Removing and replacing disks Following devices are available as replacements Replacing a failed or removed disk Replace another disk? y,n,q,? default n Then run the following command on the master node Select a disk device to enable address,list,q,? c0t2d0Enabling a disk # vxreattach -r accesname Disable another device? y,n,q,? default n Enable another device? y,n,q,? default nTaking a disk offline Renaming a disk You would use the following command to rename the diskReserving disks See the vxedit1M manual page for more information Displaying disk informationVxVM returns a display similar to the following Enter disk device or all address,all,q,? default all List disk information Menu VolumeManager/Disk/ListDiskDisplaying disk information with vxdiskadm Controlling Powerfail Timeout Setting the Pfto valuesTo set the Pfto value on a disk, use the following command Displaying the Pfto values For example, to disable Pfto on the disk c5t0d6 Enabling or disabling Pfto Controlling Powerfail Timeout Administering dynamic multipathing DMP How DMP works How DMP works Enc00 How DMP monitors I/O on paths Path failover mechanism Load balancing Throttling Use the following commands to initiate the migration DMP coexistence with HP-UX native multipathingMigrating between DMP and HP-UX native multipathing # vxvol -g diskgroup stopall Restart all the volumes in each disk group # vxvol -g diskgroup startall DMP in a clustered environment Under the new naming scheme as Disabling multipathing and making devices invisible to VxVM Disabling and enabling multipathing for specific devicesEnabling or disabling controllers with shared disk groups Enabling multipathing and making devices visible to VxVM 135 Administering dynamic multipathing DMP Displaying DMP database information Typical output from the vxdisk list command is as followsDisplaying the paths to a disk Disabled Config Disabled LogDisabled Lockrgn C1t0d3 state=enabled Type=secondary Retrieving information about a DMP node Administering DMP using vxdmpadm# vxdmpadm getdmpnode nodename=c3t2d1 Displaying the members of a LUN group # vxdmpadm getdmpnode enclosure=enc0# vxdmpadm getlungroup dmpnodename=c11t0d10 # vxdmpadm getsubpaths dmpnodename=c2t66d0 Displaying information about controllers # vxdmpadm listctlr all Displaying information about enclosures Following is example output from this commandDisplaying information about array ports Displaying information about TPD-controlled devices # vxdmpadm getsubpaths tpdnodename=emcpower10# vxdmpadm gettpdnode nodename=c7t0d10 To reset the I/O counters to zero, use this command Examples of using the vxdmpadm iostat commandGathering and displaying I/O statistics # vxdmpadm iostat start memory=4096 # vxdmpadm iostat show pathname=c3t115d0# vxdmpadm iostat show dmpnodename=c0t0d0 # vxdmpadm iostat show enclosure=Disk Setting the attributes of the paths to an enclosure # vxdmpadm setattr path c2t10d0 pathtype=active# vxdmpadm setattr path c3t10d0 pathtype=nomanual # vxdmpadm setattr path c1t20d0 pathtype=nopreferred Displaying the I/O policy Specifying the I/O policy Following policies may be set Adaptive# vxdmpadm setattr enclosure enc1 iopolicy=adaptive Adaptiveminq 048 This is the default I/O policy for Active/Active A/A arrays # vxdmpadm setattr enclosure Disk iopolicy=minimumq# vxdmpadm setattr arrayname Sena iopolicy=priority # vxdmpadm setattr arraytype A/A iopolicy=round-robin Default setting for this attribute is useallpaths=no Example of applying load balancing in a SAN# vxdmpadm setattr arrayname Disk iopolicy=singleactive # vxdisk list c3t2d15 # dd if=/dev/vx/rdsk/mydg/myvol1 of=/dev/null DMP statistics are now reset# vxdmpadm getattr enclosure ENC0 iopolicy # vxdmpadm -c-fdisable path=pathname # vxdmpadm -c-fdisable ctlr=ctlrnameDisabling I/O for paths, controllers or array ports # vxdmpadm setattr enclosure ENC0 iopolicy=singleactive # vxdmpadm enable path=pathname # vxdmpadm enable ctlr=ctlrnameEnabling I/O for paths, controllers or array ports Upgrading disk controller firmware Re-enable the plex associated with the device Renaming an enclosureStop I/O to all disks through one controller of the HBA For the other controller on the HBA, enter # vxdmpadm getattr enclosure enc0 recoveryoption Configuring the response to I/O failures# vxdmpadm setattr \ Configuring the I/O throttling mechanism # vxdmpadm setattr arraytype A/A recoveryoption=default # vxdmpadm setattr enclosure enc0 recoveryoption=nothrottle # vxdmpadm getattr enclosure HDS9500-ALUA0 recoveryoption Displaying recoveryoption valuesHDS9500-ALUA0 Error-Retry Configuring DMP path restoration policies # vxdmpadm start restore interval=seconds policy=checkall Displaying the status of the DMP path restoration thread Stopping the DMP path restoration threadThis produces output such as the following Displaying information about the DMP error-handling thread Configuring array policy modulesTo add and configure an APM, use the following command One daemon should be shown as running # vxdmpadm -r cfgapm modulename Administering DMP using vxdmpadm Creating and administering disk groups Creating and administering disk groups Specifying a disk group to commands Block special device corresponding to this volume isSystem-wide reserved disk groups To nodg Rules for determining the default disk group Displaying the system-wide boot disk group# vxdg bootdg See the vxdg1M manual page for more information Displaying disk group information # vxdg list# vxdg list diskgroup # vxdisk -s list devicename Displaying free space in a disk group Creating a disk groupFollowing is example output Adding a disk to a disk group # vxdiskadd c1t0d0# vxdg init mktdg mktdg01=c1t0d0 # vxdg -g diskgroup set cds=onoff # vxdiskunsetup devicename # vxdiskunsetup c1t0d0Removing a disk from a disk group # vxdg -g diskgroup rmdisk diskname Deporting a disk group Newdg Importing a disk group# vxdisk -s list Select disk group to import group,list,q,? default list Select another disk group? y,n,q,? default nHandling disks with duplicated identifiers VxVM Info V-5-2-374 The import of newdg was successful Option to the vxdg import command, as shown in this # vxdisk -f-g diskgroup updateudid disk# vxdisk updateudid c2t66d0 c2t67d0 Writing a new Udid to a disk # vxdg -o useclonedev=on -o updateid import mydg # vxdisk -g diskgroup settag tagname disk# vxdisk settag mytaggeddisks c2t66d0 c2t67d0 # vxdisk listtag Enabling configuration database copies on tagged disks Sample cases of operations on cloned disks# vxdg -q listmeta diskgroup # vxdg -o useclonedev=on -o tag=mytaggeddisks import mydg Importing cloned disks without tags # vxdg -g mydg set tagmeta=on tag=t1 nconfig=all nlog=all# vxdisk -o alldgs list To import only the cloned disks into the mydg disk group Symmir command is used to split off the BCV device# /usr/symcli/bin/symmir -g mydg split DEV001 # vxdg -n newdg -o useclonedev=on -o updateid import mydg Importing cloned disks with tagsState of the cloned disk is now shown as online clonedisk Disks are tagged as follows # vxdisk set EMC08 clone=off # vxdisk -o alldgs list This command results in output such as the following Renaming a disk group Dgid 774226267.1025.tweety Moving disks between disk groups# vxdg -tC -n newdg import diskgroup # vxrecover -g diskgroup -sb Moving disk groups between systems Handling errors when importing disks To clear the locks during import, use the following command# vxdisk clearimport devicename # vxdg -C import diskgroup Reserving minor numbers for disk groups Following error message indicates a recoverable error# vxdg -f import diskgroup # xvdg init newdg minor=30000 c1d0t0 c1t1d0 # vxprint -g mydg reminor Compatibility of disk groups between platforms # vxdg -g diskgroup set maxdev=4079 Handling conflicting configuration copies Example of a serial split brain condition in a cluster 191 Typical arrangement of a 2-node campus cluster Automatically Expected a = Expected B = Imported on host Y Correcting conflicting configuration information # vxsplitlines -g newdg Reorganizing the contents of disk groups Reorganizing the contents of disk groups 197 Disk group join operation Limitations of disk group split and join Moving DCO volumes between disk groups Listing objects potentially affected by a move 201 Split Snapshot Moving objects between disk groups # vxprint # vxdg -o expand move mydg rootdg mydg01 Splitting disk groups Following commands would also achieve the same result# vxdg -o expand split rootdg mydg rootdg07 rootdg08 Joining disk groups # vxdg -o overrideverify join sourcedg targetdg Following command joins disk group mydg to rootdg Disabling a disk groupMydg Mydg05 C1t96d0 Mydg06 C1t98d0 Recovering a destroyed disk group Destroying a disk groupUpgrading a disk group Use the disk group ID to import the disk group Upgrading a disk group Features supported by disk group versions # vxdg upgrade dgname To list the version of a disk group, use this command# vxdg list dgname Managing the configuration daemon in VxVM # vxdg -T 120 init newdg newdg01=c0t3d0 Backing up and restoring disk group configuration data Using vxnotify to monitor configuration changes# vxnotify -f # vxnotify -s Using vxnotify to monitor configuration changes Creating subdisks # vxmake -g mydg sd mydg02-01 mydg02,0,8000 This command provides the following output Displaying subdisk information# vxprint -st # vxprint -g diskgroup -l subdisk Splitting subdisks Moving subdisks# vxsd -g mydg mv mydg03-01 mydg12-01 mydg12-02 Associating subdisks with plexes Joining subdisks# vxmake -g diskgroup plex plex sd=subdisk # vxsd -g mydg assoc home-1 mydg02-01 mydg02-00 mydg02-01 # vxsd -g mydg -l 4096b assoc vol10-01 mydg15-01# vxsd -g mydg -l 1 assoc vol02-01 mydg11-01 # vxsd -g diskgroup assoc plex subdisk10 ... subdiskMN-1 # vxassist -g diskgroup addlog volume disk Associating log subdisks# vxsd -g diskgroup aslog plex subdisk # vxsd -g mydg aslog vol01-02 mydg02-01 To remove a subdisk, use the following command Dissociating subdisks from plexesRemoving subdisks Changing subdisk attributes # vxedit -g mydg set comment=subdisk comment mydg02-01 # vxedit -g mydg set putil0=DO-NOT-USE mydg02-01 Creating plexes # vxmake -g mydg plex vol01-02 sd=mydg02-01,mydg02-02 Displaying plex information Creating a striped plexPlex states Active plex state Clean plex stateDcosnp plex state Empty plex state Iofail plex stateLOG plex state Offline plex state Snaptmp plex state Stale plex stateTemp plex state Temprm plex state Plex condition flags Disabled plex kernel state Enabled plex kernel stateAttaching and associating plexes Plex kernel states # vxmend -g diskgroup off plex Taking plexes offline# vxmend -g mydg off vol01-02 vol02-02 Detaching plexes Reattaching plexes Start the volume using the following command # vxmend -g diskgroup fix clean plex# vxvol -g diskgroup start volume Moving plexes Copying volumes to plexes # vxplex -g diskgroup cp volume newplexDissociating and removing plexes # vxplex -g diskgroup -o rm dis plex Changing plex attributes # vxedit -g diskgroup set attribute=value ... plex# vxedit -g mydg set comment=plex comment tutil2=u vol01-02 # vxedit -g mydg set putil0=DO-NOT-USE vol01-02 Creating volumes Types of volume layouts RAID-5 Supported volume logs and maps Mirror and concatenated-mirror volumes Creating a volume Advanced approach Using vxassist Assisted approach # vxassist options make volume length attributes Vxassist Setting default values for vxassist Following is a sample vxassist defaults file Discovering the maximum size of a volume Disk group alignment constraints on volumes# vxassist -g diskgroup maxsize layout=layout attributes # vxassist -g dgrp maxsize layout=raid5 nlog=2 Creating a volume on any disk # vxassist -b -g diskgroup make volume length# vxassist -b make voldefault 10g # vxprint -g diskgroup -G -F %align # vxassist -b -g mydg make volspec 5g mydg03 mydg04 Creating a volume on specific disks# vxassist -b -g mydg make volspec 5g ctlrc1 !targetc1t5 Specifying ordered allocation of storage to volumes Mydg01 mydg02 mydg03 mydg04 mydg05 mydg06 mydg07 mydg08 Stripe volume Volume across controllers Creating a mirrored volume Creating a mirrored-concatenated volumeCreating a concatenated-mirror volume # vxassist -b -g mydg make volmir 5g layout=mirror Creating a volume with a version 0 DCO volume # vxvol -g diskgroup set logtype=drldrlseq volume # vxdg -T 90 upgrade diskgroupFor more information, see Upgrading a disk group on Creating a volume with dirty region logging enabled Creating a volume with a version 20 DCO volume# vxdg upgrade diskgroup # vxassist -b -g diskgroup make volume length layout=stripe Creating a striped volume# vxassist -b -g mydg make volzebra 10g layout=stripe Creating a mirrored-stripe volume Creating a striped-mirror volume Mirroring across targets, controllers or enclosures Creating a RAID-5 volume # vxassist -b -g mydg make volraid 10g layout=raid5 nlog=2 # vxassist -g diskgroup listtag volume Creating tagged volumes# vxassist -g diskgroup list tag=tagname volume Creating a volume using vxmake Creating a volume using a vxmake description file # vxmake -g diskgroup -d descriptionfile # vxassist -b -g diskgroup make volume length layout=mirror Initializing and starting a volumeMydg04-021/8000,mydg04-031/16000 Initializing and starting a volume created using vxmake # vxvol -g diskgroup init enable volume# vxvol -g diskgroup init active volume # vxvol -g diskgroup init zero volume Accessing a volume Administering volumes Vxprint command can also be applied to a single disk group Displaying volume informationThis is example output from this command Volume states Active volume stateClean volume state Empty volume state Volume kernel states Invalid volume stateNeedsync volume state Replay volume state Detached volume kernel state Disabled volume kernel stateEnabled volume kernel state Monitoring and controlling tasks Managing tasks with vxtask Vxtask operations Using the vxtask command Stopping a volume Putting a volume in maintenance mode Adding a mirror to a volume Starting a volumeTo start all Disabled volumes, enter Mirroring all volumes Mirroring volumes on a VM disk# /etc/vx/bin/vxmirror -g diskgroup -a # /etc/vx/bin/vxmirror -d yes Mirror volumes on another disk? y,n,q,? default n # vxassist -gdiskgroup remove mirror volumeRemoving a mirror At the following prompt, press Return to make the mirror Adding logs and maps to volumes Preparing a volume for DRL and instant snapshots Specifying storage for version 20 DCO plexes Using a DCO and DCO volume with a RAID-5 volume # DCONAME=‘vxprint -g diskgroup -F%dconame volume‘Determining the DCO version number # vxprint -g diskgroup -F%version $DCONAME Determining if DRL is enabled on a volume Determining if DRL logging is active on a volumeThis command returns on if DRL logging is enabled Disabling and re-enabling DRL To re-enable DRL on a volume, enter this command Upgrading existing volumes to use version 20 DCOsTo re-enable sequential DRL on a volume, enter Use the following command on the volume to upgrade it Adding traditional DRL logging to a mirrored volume To remove a DRL log, use the vxassist command as follows # vxassist -g mydg addlog volume logtype=drlseq nlog=nRemoving a traditional DRL log # vxassist -g mydg addlog vol03 logtype=drl Adding a RAID-5 log using vxplex # vxassist -b -g diskgroup addlog volume loglen=lengthAdding a RAID-5 log # vxassist -g mydg addlog volraid Resizing a volume # vxprint -g diskgroup -ht volume# vxassist -g diskgroup maxgrow volume Removing a RAID-5 log Resizing volumes using vxresize Online JFS Full Base JFS LiteVxFS Mounted File System Unmounted File System Extending to a given length Resizing volumes using vxassistExtending by a given length Shrinking to a given length Resizing volumes using vxvolShrinking by a given length Setting tags on volumes # vxassist -g diskgroup removetag volume tagname Changing the read policy for mirrored volumes Moving volumes from a VM disk Removing a volumeTo set the read policy to select, use the following command To move volumes from a disk Move volumes from another disk? y,n,q,? default nVxVM vxevac Info VxVM Info V-5-2-188 Evacuation of disk mydg02 is complete Enabling FastResync on a volume # vxvol -g diskgroup set fastresync=on volume Checking whether FastResync is enabled on a volume # vxprint -g diskgroup -F%fastresync volume# vxprint -g diskgroup -F%hasdcolog volume Disabling FastResync Performing online relayout # vxassist -g mydg relayout vol02 layout=stripe Permitted relayout transformations Supported relayout transformations for RAID-5 volumes Relayout to From raid5 ConcatRelayout to From mirror-concat Concat Mirror-concat Mirror-stripe Layered striped-mirror volumes Relayout to From mirror-stripe ConcatSupported relayout transformations for unmirrored stripe Relayout to From stripe or stripe-mirror Concat Specifying a non-default layout Specifying a plex for relayoutTagging a relayout operation # vxassist -g fsgrp relayout vol04 layout=raid5 ncol=4 Viewing the status of a relayout To resume the operation, use the vxtask commandControlling the progress of a relayout Converting between layered and non-layered volumes # vxrelayout -g mydg -o bg,slow=1000,iosize=10m start vol04# vxrelayout -g mydg -o bg reverse vol04 # vxassist -g mydg relayout vol1 ncol=5 # vxassist -g mydg convert vol1 layout=mirror-stripe Converting between layered and non-layered volumes Administering volume snapshots Administering volume snapshots Independent Volume Vxassist snapclear Traditional third-mirror break-off snapshots Traditional third-mirror break-off snapshots Full-sized instant snapshots 308 Administering volume snapshots Space-optimized instant snapshots Cycle Start Vxsnap make Vxsnap refresh Vxsnap prepare Emulation of third-mirror break-off snapshots Linked break-off snapshot volumes Cascaded snapshots Cascaded snapshots Creating a snapshot of a snapshot Creating a snapshot of a snapshot Create instant snapshot S2 of S1 Vxsnap make source=S1 Vxsnap dis S2 Restoring the original volume from a snapshot Creating multiple snapshots Restoring the original volume from a snapshot Creating instant snapshots Creating instant snapshots Preparing to create instant and break-off snapshots Creating a shared cache object # LEN=‘vxprint -g diskgroup -F%len volume‘ For example to start the cache object, cobjmydg# vxcache -g mydg start cobjmydg # RSZ=‘vxprint -g diskgroup -F%regionsz $DCONAME‘ Creating and managing space-optimized instant snapshots Creating instant snapshots # fsck -F vxfs /dev/vx/rdsk/diskgroup/snapshot Creating and managing full-sized instant snapshots # vxsnap -g mydg make source=myvol/snapvol=snap1myvol# vxsnap -g diskgroup syncwait snapvol # vxsnap -g mydg syncwait snap2myvol # vxprint -gdiskgroup -F%incompletesnapvol Creating and managing third-mirror break-off snapshots # vxsnap -g mydg addmir vol1 nmirror=2 alloc=mydg10,mydg11 # vxsnap -g mydg snapwait vol1 nmirror=2 Creating and managing linked break-off snapshot volumes # vxsnap -g diskgroup -b addmir volume mirvol=snapvol \ Mirdg=snapdg Reattach the snapshot volume with the original volume. See Creating multiple instant snapshots# vxsnap -g diskgroup make \ # vxsnap -g diskgroup make source=vol1/snapvol=snapvol1 \ # vxvset -g mydg list vset1 Creating instant snapshots of volume sets# vxvset -g mydg list snapvset1 Svol1 409600 Svol0 204800Svol2 614400 Removing a snapshot mirror Adding snapshot mirrors to a volume# vxsnap -g mydg rmmir vol1 Removing a linked break-off snapshot volume Adding a snapshot to a cascaded snapshot hierarchyRefreshing an instant snapshot # vxsnap -g mydg rmmir vol1 mirvol=prepsnap mirdg=mysnapdg Reattaching an instant snapshot # vxsnap -g mydg reattach snapmyvol source=myvol nmirror=1 Reattaching a linked break-off snapshot volume # vxsnap -g mydg snapwait myvol nmirror=1 Restoring a volume from an instant snapshot # vxsnap -g mydg restore myvol source=snap3myvolDissociating an instant snapshot # vxsnap -g snapdg snapwait myvol mirvol=prepsnap Removing an instant snapshot Splitting an instant snapshot hierarchy# vxsnap -g mydg dis snap2myvol # vxedit -g mydg -r rm snap2myvol Displaying instant snapshot information # vxsnap -g mydg split snap2myvol# vxsnap -g diskgroup print vol # vxsnap -g mydg print # vxsnap -g diskgroup -l -v -x list vol # vxsnap -g dg -vx list Controlling instant snapshot synchronization Vxsnap -g diskgroup syncresume \Vxsnap -b -g diskgroup syncstart \ Vxsnap -g diskgroup syncstop vol volset Improving the performance of snapshot synchronization Listing the snapshots created on a cache# vxcache -g diskgroup listvol cacheobject Tuning the autogrow attributes of a cache # vxcache -g mydg set highwatermark=60 cobjmydg Growing and shrinking a cache Finally, remove the cache object and its cache volumeRemoving a cache Creating traditional third-mirror break-off snapshots # vxassist -g diskgroup snapwait volume # vxassist -b -g diskgroup snapstart nmirror=N volume# vxassist -g diskgroup snapstart voldef Create a snapshot volume using the following command # vxassist -g diskgroup snapshot nmirror=N volume snapshot# vxassist -g diskgroup snapshot voldef snapvol # vxedit -g diskgroup -rf rm snapshot Converting a plex into a snapshot plex Reattaching a snapshot volume Creating multiple snapshots# vxplex -g diskgroup convert state=SNAPDONE plex # vxassist -g diskgroup -o allvols snapshot # vxassist -g diskgroup -o allplexes snapback snapshot Adding plexes to a snapshot volume# vxassist -g diskgroup snapback nmirror=number snapshot # vxprint -g diskgroup -F%rid $DCOVOL Dissociating a snapshot volume# vxassist snapclear snapshot Output from this command is shown in the following examples # vxassist snapprint volumeDisplaying snapshot information # vxassist -g mydg snapprint Adding a version 0 DCO and DCO volume Specifying storage for version 0 DCO plexes # vxdco -g diskgroup -o rm dis dcoobj Removing a version 0 DCO and DCO volume# vxdco -g mydg dis myvoldco For more information, see the vxdco1M manual Reattaching a version 0 DCO and DCO volume# vxdco -g mydg att myvol myvoldco Adding a version 0 DCO and DCO volume Creating and administering volume sets Creating a volume set Adding a volume to a volume set Listing details of volume sets Stopping and starting volume sets Removing a volume from a volume set Raw device node access to component volumes# vxvset -g diskgroup -f rmvol volset volume # vxvset -g mydg start set1 # vxvset -g mydg list set1 Enabling raw device access when creating a volume set Controlling raw device access for an existing volume set Displaying the raw device access settings for a volume set# vxvset -g diskgroup -fset makedev=onoff vset # vxvset -g mydg set makedev=on myvset2 # vxvset -g mydg set compvolaccess=read-write myvset2# vxvset -g mydg set makedev=off myvset2 Raw device node access to component volumes Configuring off-host processing Implementing off-host processing solutions Example implementation of off-host processing Implementing off-host online backup # vxprint -g volumedg -F%instant volume # vxvol -g volumedg set fastresync=on volume # vxdg import snapvoldg # vxdg deport snapvoldg# fsck -F vxfs /dev/vx/rdsk/snapvoldg/snapvol # vxprint -g volumedg -F%instantvolume # vxsnap -g volumedg snapwait volume mirvol=snapvolImplementing decision support 375 # mount -F vxfs /dev/vx/dsk/snapvoldg/snapvol \ mountpoint You can then resume the procedure from on Implementing off-host processing solutions Administering hot-relocation How hot-relocation works 381 Mydg05 # vxrecover -b -g mydg home src Partial disk failure mail messages# vxstat -g mydg -s -ff home-02 src-02 Sd mydg01-04 Sd mydg01-06 Sd mydg02-03 Sd mydg02-04 How space is chosen for relocation Complete disk failure mail messagesFailing disks mydg02 Configuring a system for hot-relocation # vxdg -g diskgroup spare Displaying spare disk informationMydg mydg02 C0t2d0 658007 Marking a disk as a hot-relocation spare Mark another disk as a spare? y,n,q,? default n# vxedit -g mydg set spare=on mydg01 Where diskname is the disk media name Removing a disk from use as a hot-relocation spareExcluding a disk from hot-relocation use Following confirmation is displayed To use vxdiskadm to exclude a disk from hot-relocation use Making a disk available for hot-relocation use# vxedit -g diskgroup set nohotuse=off diskname Configuring hot-relocation to use only spare disks Moving and unrelocating subdisksSpare=only To root Subject Attempting VxVM relocation on host teal Moving and unrelocating subdisks using vxdiskadm Unrelocate to a new disk y,n,q,? default nStatus message is displayed at the end of the operation Enter the original disk name disk,list,q,? Moving and unrelocating subdisks using vxunreloc Moving and unrelocating subdisks using vxassist# vxassist -g mydg move home !mydg05 mydg02 Moving hot-relocated subdisks back to a different disk Moving hot-relocated subdisks back to their original diskForcing hot-relocated subdisks to accept different offsets Examining which subdisks were hot-relocated from a disk Restarting vxunreloc after errors# vxprint -g mydg -se sdorigdmname=mydg01 Nohup vxrelocd -o slow=IOdelay root Modifying the behavior of hot-relocation# nohup vxrelocd root Nohup vxrelocd root user1 user2 See the vxrelocd1M manual page for more information Alternatively, you can use the following command# nohup /etc/vx/bin/vxrelocd root user1 user2 Administering cluster functionality Overview of cluster volume management 399 Example of a 4-node cluster Private and shared disk groups Two types of disk groups are defined Activation modes of shared disk groups Exclusivewrite ewReadonly ro Sharedread sr Activation mode Description Enableactivation=true Defaultactivationmode=activation-modeActivation modes for shared disk groups Sharedwrite sw Connectivity policy of shared disk groups Global detach policy Local detach policy Disk group failure policy Guidelines for choosing detach and failure policies Effect of disk connectivity on cluster reconfiguration Limitations of shared disk groups Cluster initialization and configuration Cluster reconfiguration Vxclustadm utility Various reasons that may be given are shown in Table# /etc/vx/bin/vxclustadm nodestate state out of cluster Reason user initiated stop Node abort messages Reason Description Volume reconfiguration Vxconfigd daemon Vxconfigd daemon recovery # hagrp -freeze group # hagrp -unfreeze group Node shutdown Node abort Multiple host failover configurationsCluster shutdown Import lock Failover Corruption of disk group configuration Where the reason can describe errors such as Administering VxVM in cluster environments # vxdctl -c modeRequesting node status and discovering the master node See the vxdctl1M manual page for more information Example output from this command is displayed here Example output from this command is as followsDetermining if a disk is shareable Listing shared disk groups Creating a shared disk group # vxdg -s init diskgroup diskname=devicename Importing disk groups as shared Forcibly importing a disk group# vxdg -s import diskgroup # vxdg -s -f import diskgroup Converting a disk group from shared to private Changing the activation mode on a shared disk group Setting the disk detach policy on a shared disk groupDefault disk detach policy is global # vxdg -g diskgroup set activation=mode Creating volumes with exclusive open access by a node Setting exclusive open access to a volume by a node# vxdg -g diskgroup set dgfailpolicy=dgdisableleave # vxvol -g dskgrp set exclusive=on volmir This command produces output similar to the following This command produces out put similar to the followingDisplaying the cluster protocol version Displaying the supported cluster protocol version range Upgrading the cluster protocol version Recovering volumes in shared disk groupsObtaining cluster performance statistics Vol Vol1 2421 600000 99.0 # vxstat -b Administering VxVM in cluster environments Administering Sites and remote mirrors Site-consistent volume with two plexes at each of two sites Example of a two-site configuration with remote storage only Configuring site-based allocation on a disk group Configuring sites for hosts and disksTo remove the site name from a host, use this command Configuring site consistency on a disk group Configuring site consistency on a volume# vxdg -g diskgroup set siteconsistent=on # vxdg -g diskgroup set siteconsistent=off Site-based allocation of storage to volumes Setting the siteread policy on a volumeRAID-5 volumes in a site-consistent disk group # vxassist -g diskgroup make volume size mirror=site Examples of storage allocation using sites Command Description Turn on site consistency for each volume in the disk group Making an existing disk group site consistentRegister a site record for each site with the disk group Turn on site consistency for the disk group Fire drill testing the configuration Recovery from simulated site failureAutomatic site reattachment Simulating site failure # ps -afe Failure scenarios and recovery procedures# kill -9 PID Recovery from a loss of site connectivity Recovery from host failureRecovery from storage failure Failure scenario Recovery technique Recovery from site failure Failure scenarios and recovery procedures About Storage Expert See the vxse1M manual Before using Storage Expert How Storage Expert worksRunning Storage Expert One of the following keywords must be specified Displaying rule attributes and their default values Discovering what a rule doesRunning a rule # vxsestripes2 info Setting rule attributes Rule result types Identifying configuration problems using Storage Expert Recovery time Checking for non-mirrored RAID-5 logs vxseraid5log3 Checking minimum and maximum RAID-5 log sizes vxseraid5log2Vxseraid5log1 Checking disk group configuration copies and logs vxsedg2 Checking on disk config size vxsedg3Disk groups Checking the version number of disk groups vxsedg4 Checking states of plexes and volumes vxsevolplex Checking volume redundancy vxseredundancyChecking for non-imported disk groups vxsedg6 Volumes needing recovery Checking the number of columns in RAID-5 volumes vxseraid5Disk striping Disk sparing and relocation management Hardware failuresRootability System name Checking the system name vxsehost Rule definitions and attributes Rule Description See Running a rule on Rule Attribute Default Description Value Nsdthreshold Vxseraid5 Toonarrowraid5Toowideraid5 R5maxsize Vxseredundancy Volumeredundancy Vxsestripes1 Default stripeunitVxserootmir Vxsespares Vxsevolplex Rule definitions and attributes Performance guidelines Data assignment Striping Mirroring Combining mirroring and striping RAID-5 Volume read policies Performance monitoring Setting performance prioritiesObtaining performance data Printing volume statistics Tracing volume operationsBy vxtrace Using performance data Using I/O statistics Following is an extract from typical output # vxprint -g mydg -tvh archiveMydg03-03 Archive-01 40960 C1t2d0 # vxassist -g mydg move archive !mydg03 destdisk 471 General tuning guidelines Tuning VxVMUsing I/O tracing Tuning guidelines for large systems Number of configuration copies for a disk group # vxedit set nconfig=5 bigdg Changing the values of tunables# vxdmpadm settune dmptunable=value # vxdmpadm gettune dmptunable Tunable parameters Dmppathswitchblksshift DmphealthtimeDmploglevel Dmppathage Dmprestorecycles DmprestoreintervalDmpprobeidlelun Dmpqueuedepth Dmprestorepolicy DmpretrytimeoutDmpscsitimeout Dmpretrycount Volcheckptdefault VoldefaultiodelayDmpstatinterval Volfmrlogsz Volmaxio VolmaxvolVolmaxioctl Volmaxspecialio VolmaxparallelioVolsubdisknum Volcvmsmartsync VoldrlmaxdrtregsVoldrlmaxseqdirty Voldrlminregionsz Voliotiobufdefault VoliomemmaxpoolszVolioterrbufdflt Voliotiobuflimit Voliotmaxopen VoliotiobufmaxVolpagemodmaxmemsz Volraidminpoolsz Volraidrsrtransmax Tuning VxVM Commands summary If you are using a C shell csh or tcsh, use the commands Vxdisk -g diskgroup list diskname # vxdisk -g mydg listVxdg list diskgroup # vxdg list mydg Table A-2 Administering disks Command Description # vxedit -g mydg rename \ Mydg03 mydg02# vxedit -g mydg set \ Reserve=on mydg02 # vxdiskunsetup c0t3d0 Spare=on mydg04Spare=off mydg04 # vxdisk offline c0t1d0 # vxdg init mydg \ Mydg01=c0t1d0# vxsplitlines -g mydg # vxdg -n newdg deport mydg # vxdg -o expand listmove \ Mydg newdg myvol1Newdg myvol1 Newdg myvol2 myvol3 # vxrecover -g mydg -sb # vxdg destroy mydg# vxmake -g mydg sd \ Mydg02-01 mydg02,0,8000 # vxsd -g mydg assoc \ Vol01-01 mydg10-010 \Mydg11-011 mydg12-012 Mydg02-01 # vxsd -g mydg -o rm dis \ # vxmake -g mydg plex \Vol01-02 \ Sd=mydg02-01,mydg02-02 # vxplex -g mydg mv \ Vol01-02Vol02-02 vol02-03 Table A-6 Creating volumes Command Description # vxplex -g mydg cp vol02 \Vol03-01 Vol02-02 Volume length layout=striperaid5 \ Vxassist -b -g diskgroup make \Stripeunit=W ncol=N attributes Mysvol 20g layout=stripe \ # vxmake -g mydg -Uraid5\ Vol r5vol \Plex=raidplex,raidlog1,\ Raidlog2 Table A-7 Administering volumes Command Description Drl=onsequentialoff # vxsnap -gmydg prepare \ myvol drl=on # vxassist -g mydg make \ Cvol 1g layout=mirror \Init=active mydg16 mydg17 Cachevolname=cvol # vxsnap -g mydg unprepare \ myvol # vxassist -gmydg relayout \ vol2 layout=stripeVol3 layout=raid5 \ Stripeunit=16 ncol=4 # vxrecover -g mydg \ # vxassist -g mydg remove \ myvolMytask -b mydg05 # vxtask -h -g mydg list # vxtask pause mytask # vxtask -p -g mydg list# vxtask resume mytask # vxtask abort mytask Administrative commands Online manual pages Table A-9 Manual pages Name Description Vxrecover VxmendVxmirror Vxnotify File formats Device driver interfaces Configuring Veritas Volume Manager Setup tasks after installation Adding foreign devices Adding unsupported disk arrays as JBODsAdding disks to disk groups Guidelines for configuring storage Mirroring guidelines Dirty region logging guidelines Striping guidelines RAID-5 guidelines Hot-relocation guidelines 517 Accessing volume devices Configuring cluster supportControlling VxVM’s view of multipathed devices Configuring shared disk groups Converting existing VxVM disk groups to shared disk groups Reconfiguration tasks Glossary Single copy of a configuration database Page See disk enclosure Jbod Page RAID Page Page Page Index CDS Page CVM Page Page DMP Empty Page Page Page Page Iofail 228 Nodarec 228 Nodevice 228 Recover 228 Removed Page Page Page Page Page TPD Page Detached Disabled Enabled Page Page Page Page Page