LVM Migration from Legacy to Agile Naming Model

ManualsBrandsHP ManualsSoftwareHP-UX 11i Volume Management (LVM/VxVM) Software

HP-UX 11i v3

Abstract ..............................................................................................................................................2

Legacy and Agile Naming Models .........................................................................................................3

LVM support for Dual Naming Models ................................................................................................3

Naming Model specific Commands/Options.......................................................................................3

Disabling Legacy Naming Model .......................................................................................................4

Impact on LVM commands after the Disablement of Legacy Naming Model.............................................4

Impact of Native Multi-Pathing on LVM ...................................................................................................4

LVM Alternate Links (PVlinks) ..............................................................................................................5

Restoring LVM’s Legacy Alternate Link Behavior ...................................................................................5

LVM Online Disk Replacement (OLR) ...................................................................................................6

Volume Group DSF Migration................................................................................................................8

Migration Alternatives.......................................................................................................................8

Migration of a Clustered Volume Group..............................................................................................9

Migration using vgdsf .......................................................................................................................9

Migration Procedure .......................................................................................................................10

A Typical Migration Operation ............................................................................................................12

Glossary ...........................................................................................................................................14

For More Information..........................................................................................................................15

Appendix : Using vgdsf.......................................................................................................................16

Call to Action ....................................................................................................................................18

Summary of content (18 pages)

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LVM Migration from Legacy to Agile Naming Model HP-UX 11i v3 Abstract ..............................................................................................................................................2 Legacy and Agile Naming Models .........................................................................................................3 LVM support for Dual Naming Models ................................................................................................
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Abstract This white paper discusses the migration of LVM volume group configurations from legacy to the agile naming model. The agile naming model is a new representation for mass storage devices, introduced in HP-UX 11i v3. Legacy naming model is the naming model used in releases prior to HP-UX 11i v3. This document is intended for system administrators or operators who have experience with both HP-UX and LVM.
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Legacy and Agile Naming Models In versions prior to HP-UX 11i v3, the Device Special Files (DSFs) of mass storage devices were bound to the path of the device. This representation of mass storage devices still exists in HP-UX 11i v3, and is referred as the legacy view. HP-UX 11i v3 introduces a new representation for mass storage devices called the agile view.
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to migrate a volume group configured with legacy DSFs to use corresponding persistent DSFs. Disabling Legacy Naming Model The rmsf –L command disables the legacy naming model by removing all legacy DSFs and related configuration information. For additional information on disabling legacy naming model in HP-UX 11i v3, see the For More Information section for the white paper HP-UX 11i v3 Persistent DSF Migration Guide.
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Storage. This is the default behavior in the case of active/active devices, irrespective of the naming model used. Some active/passive devices may be supported by the mass storage stack but will be managed by the respective vendor delivered plug-in modules. For additional information on writing active/passive device plug-ins in HP-UX 11i v3, see the For More Information section for the white paper HP-UX 11i v3 Writing Active/Passive Switch Plug-Ins.
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# vgdisplay -v -F vg01 | grep pv_name pv_name=/dev/disk/disk5:pv_status=available:total_pe=243:free_pe=242:autoswitch=On 2. Find legacy DSFs corresponding to the persistent DSF: # ioscan -m dsf /dev/disk/disk5 Persistent DSF Legacy DSF(s) ======================================== /dev/disk/disk5 /dev/dsk/c2t1d0 /dev/dsk/c3t1d0 3. Add legacy DSFs as alternate links to the persistent DSF: # vgextend vg01 /dev/dsk/c2t1d0 /dev/dsk/c3t1d0 4.
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In previous HP-UX releases (that is, HP-UX 11i v2 or earlier), a specific path or all paths to a physical volume can be detached (disabled) using –n and –N options of the pvchange command, respectively. The detached path or the physical volume will not be accessed by LVM, but remain configured in the volume group.
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Volume Group DSF Migration In HP-UX 11i v3, HP recommends the use of persistent DSFs over legacy, in LVM volume group configurations. A migration operation is required for existing volume groups already configured with legacy DSFs. Migration involves reconfiguration of existing volume groups with corresponding persistent DSFs, in place of legacy DSFs. DSF migration should be performed one volume group at a time, and should be completed for all volume groups.
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Following the invocation of vgscan -B command, use vgchange to reactivate the corresponding volume group. This reconfigures the volume group with the DSFs (both legacy and persistent DSFs corresponding to each of the physical volume) in the /etc/lvmtab file. Legacy DSFs can later be removed using vgreduce, leaving behind corresponding persistent DSFs. This facilitates a phased DSF migration from legacy to agile naming model, while the volume group continues to remain active.
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• • • • Identify all legacy DSFs configured in the volume group, using vgdisplay –v. Ignore alternate links. For each legacy DSF found, find its corresponding persistent DSF, using ioscan –m dsf . If the persistent DSF is already part of the volume group configuration, continue for this particular DSF, with the step 2 - “Reduce the volume group of all legacy DSFs”. If a physical volume is configured with 8 paths 1 (alternate links), remove one using vgreduce.
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else echo Volume Group $VG is not active and cannot be migrated.
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A Typical Migration Operation 1. Identify volume groups for migration: a) Activate deactivated volume groups: In this example, volume group vg01 is not active. Activate it. # vgdisplay -F | grep -E "vg_status=deactivated" vg_name=/dev/vg01:vg_status=deactivated # vgchange -a y vg01 Activated volume group Volume group "vg01" has been successfully changed. b) Identify volume groups configured with legacy DSFs. Only the ones configured with legacy DSFs must be migrated.
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Persistent DSF /dev/disk/disk60 added to VG /dev/vg01 Persistent DSF /dev/disk/disk61 added to VG /dev/vg01 Legacy DSF /dev/dsk/c10t0d1 removed from VG /dev/vg01 Legacy DSF /dev/dsk/c19t0d1 removed from VG /dev/vg01 Legacy DSF /dev/dsk/c21t0d1 removed from VG /dev/vg01 Legacy DSF /dev/dsk/c8t0d1 removed from VG /dev/vg01 Legacy DSF /dev/dsk/c8t0d4 removed from VG /dev/vg01 Legacy DSF /dev/dsk/c8t0d5 removed from VG /dev/vg01 Legacy DSF /dev/dsk/c8t0d6 removed from VG /dev/vg01 Volume Group configuration for
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Glossary Active/Active device An active/active device has two or more ports to the same LUN, both of which can be accessed simultaneously. Active/Passive device Also known as asymmetric active/active device. Though the same LUN has multiple ports, unlike an active/active device, only the primary port should be used for LUN access at any time. Agile Addressing The ability to address a LUN with the same device special file regardless of the physical location of the LUN or the number of paths leading to it.
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For More Information To learn more about the agile view, mass storage, DSF migration and LVM OLR on HP-UX, see the following documents on the HP documentation website: http://docs.hp.
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Appendix : Using vgdsf NAME vgdsf – Script to migrate a LVM volume group from legacy to agile naming model. SYNOPSIS /usr/contrib/bin/vgdsf {-a | -d | -c} vg_name DESCRIPTION Migrate the volume group from legacy to the persistent DSF naming model. The volume group vg_name should be active and can be in use during the migration operation. All legacy DSFs in the volume group vg_name, will be replaced by their corresponding persistent DSFs.
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/usr/contrib/bin/vgdsf –d /dev/vg_name SEE ALSO intro(7), lvm(7), vgcreate(1M), vgextend(1M), vgdisplay(1M), pvdisplay(1M) 17
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Call to Action HP welcomes your input. Please give us comments about this white paper, or suggestions for mass storage or related documentation, through our technical documentation feedback website: http://docs.hp.com/en/feedback.html © 2007 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services.