HP-UX 11i v3 LVM New Features in HP-UX 11i v3 (September 2009)

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

11i v3 LVM New Features in HP-UX

Abstract................................................................................................................................................................

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pvdisplay – Displays user data offset and checks if disk is under HP-UX LVM control

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vgscan - Scans Faster, Per Volume Group Scanning and Supports Persistent DSF

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vgcfgrestore – Enhanced Listing of Backup File Contents

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Error Management Technology (EMT)

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Long Host Name Support for Display Commands

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lvmadm Command

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vgremove – Removal of Volume Group Device Files

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vgdisplay – Displays More Information

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New functionality ........................................................................................................................

of Mass StorageSupport for Agile View

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Multipathing and Alternate Links (PVlinks)

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Dynamic LUN Expansion (DLE)

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Modification of Volume Group Settings

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Modification of Physical Volume Type (Boot/Non-Boot)

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SLVM Online Reconfiguration

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LVM Device Online Replacement (OLR)

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Volume Group Quiesce and Resume

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Boot Resiliency

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Striped and Mirrored Logical Volumes

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Better Coexistence with Other Disk Users

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Better Utilization of Disk Space – No Bad Block Reserve Area

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Elimination of maxvgs Tunable

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Proactive Polling of Alternate links

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Version 2.x Volume Groups

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Boot Disk Configuration Self Healing

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Performance Improvements......................................................................................................

Mirror Write Cache (MWC) Enhancements

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LVM Support for Large I/O Sizes

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Parallel Resynchronization of Stale Extents

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Parallel Open of Physical Volumes

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Increased Limits..........................................................................................................................

Maximum Logical Volume Size Increased up to 16TB

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Increased Limits for Version 2.x Volume Groups

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Usability Enhancements.............................................................................................................

Compact, Parsable Command Output

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Summary of content (35 pages)

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LVM New Features in HP-UX 11i v3 Abstract ................................................................................................................................................................ 3 New functionality ................................................................................................................................................ 4 Support for Agile View of Mass Storage ......................................................................................................
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Auto Creation of Volume Group File ................................................................................................................. 30 pvmove Enhancements .................................................................................................................................... 30 Miscellaneous.....................................................................................................................................................
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Abstract In HP-UX 11i v3 (11 .31), LVM delivers significant performance, scalability, usability, and availability enhancements. After the initial release of HP-UX 11i v3 in February 2007, there have been three updates of HP-UX 11i v3:September 2007, March 2008, and September 2008. This whitepaper lists all the new LVM features in the initial release and the three updates of HP-UX 11i v3. Some features have their own whitepaper; this document only summarizes them.
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New functionality Support for Agile View of Mass Storage HP-UX 11i v3 introduces a new representation of mass storage devices called the agile view. In this representation, the device special file (DSF) name for each disk no longer contains path (or link) information. The multipathed disk has a single persistent DSF regardless of the number of physical paths to it. The legacy view, represented by the legacy DSF, continues to exist.
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LVM introduces two new options: -a (to indicate an online operation) and -E (to handle a DLE operation explicitly). For more information, see vgmodify(1M) and the - LVM Volume Group Dynamic LUN expansion (DLE)/vgmodify whitepaper. pvmove(1M) The pvmove command was enhanced in the February 2007 release of HP-UX 11i v3 to allow relocation of just the first extent of the physical volume. The vgmodify command uses this additional space to expand the LVM’s ondisk configuration information.
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Consider a volume group with one physical volume and one logical volume as follows: # vgdisplay -v /dev/vgdatabase --- Volume groups --VG Name /dev/vgdatabase VG Write Access read/write VG Status available Max LV 255 Cur LV 1 Open LV 1 Max PV 16 Cur PV 1 Act PV 1 Max PE per PV 2559 VGDA 2 PE Size (Mbytes) 4 Total PE 2559 Alloc PE 10 Free PE 2549 Total PVG 0 Total Spare PVs 0 Total Spare PVs in use 0 −-- Logical volumes --LV Name LV Status LV Size (Mbytes) Current LE Allocated PE Used PV /dev/vgtest/lvol1 a
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The previous output shows that you can change the “Max PE per PV” value to 6652 with the value of “Max PV” retained at 16. To increase the value of “Max PV” (with the current available space for LVM configuration data), it might be necessary to reduce the value of “Max PE per PV”. Use the –t option of the vgmodify command to check if the “Max PV” value can be increased by changing the value of “Max PE per PV”.
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Starting the modification by writing to all Physical Volumes Applying the configuration to all Physical Volumes from "/etc/lvmconf/vgtest.conf" Completed the modification process. New Volume Group configuration for "vgtest" has been saved in "/etc/lvmconf/vgtest.conf.old" Volume group "vgtest" has been successfully changed.
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The vgmodify command enables you to change a physical volume type from boot to non-boot or vice versa. See vgmodify(1M) and pvcreate(1M) for the -B option. Also see the LVM Volume Group Dynamic LUN expansion (DLE)/vgmodify whitepaper. Note that making a physical volume non-bootable increases the space available on that device for LVM configuration data. However, to take advantage of the additional space, you must mark every disk in a volume group non-bootable.
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For more information, see the LVM Volume Group Quiesce/Resume whitepaper. Boot Resiliency Root volume group scanning is a new LVM feature in HP-UX 11i v3. The feature can prevent boot failures that can occur on prior HP-UX releases. During boot, the root volume group activation can fail if the LVM boot configuration information is incorrect or outof-date with the systems current I/O configuration.
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Figure 1: RAID 1+0 and RAID 0+1 The advantages of hardware-based RAID 10 over RAID 01: • • When one disk fails and is replaced, only the amount of data on this disk needs to be copied or resynchronized. RAID 10 is more tolerant to multiple disk failures before data becomes unavailable. The advantages of hardware-based RAID 01 over RAID 10: • • Simpler to configure striped volumes and then extend mirroring. Able to split the mirror copy and have two usable volume sets.
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You can create a new striped and mirrored logical volume from scratch, or extend (add mirror to) an existing striped logical volume. With the use of physical volume groups (PVGs), mirroring and striping can be directed to specific physical volumes. Without the constraint created by the nesting of levels in hardware based RAID solutions, LVM is combining the striping and mirroring processing, which allows LVM to provide the best of both RAID 10 and RAID 01.
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Contents of /etc/lvmpvg V G /d e v/v g t es t PVG PVG0 /dev/dsk/c2t0d0 /dev/dsk/c2t1d0 PVG PVG1 /dev/dsk/c3t0d0 /dev/dsk/c3t1d0 • Adding a mirror to existing striped logical volumes.
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Compatibility Note Releases prior to HP-UX 11i v3 only support striped or mirrored logical volumes and do not support combination of striped and mirrored logical volumes. If a logical volume using simultaneous mirroring and striping is created on HP-UX 11i v3, attempts to import or activate its associated volume group fails on a previous HP-UX release.
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Compatibility Note In HP-UX 11i v3, LVM is compatible with physical volumes that already have entries in the bad block directory. For example, a disk device is configured for LVM on HP-UX 11i v2 and this physical volume has bad blocks relocated to the BBRA. On importing such a physical volume onto a HP-UX 11i v3 release, LVM continues to support this physical volume and can read the relocated blocks from the BBRA.
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Proactive Polling of Alternate links With September 2007 release of HP-UX 11i v3, LVM supports a new -p command line option in the pvchange command, which controls the way LVM monitors alternate links to a multipathed physical volume. By default, LVM proactively monitors the health of all configured links. If auto-switchback is enabled (by default), this polling helps LVM detect and switch to a better link when it becomes available.
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Performance Improvements Mirror Write Cache (MWC) Enhancements The MWC allows a fast resynchronization of data following a system crash or failure. The MWC keeps track of where I/O writes are occurring on the volume group and periodically records this activity in an on-disk data structure. An extra disk write is required for every mirrored write not already recorded on the physical volume. Upon system reboot after crash, the operating system uses the MWC to resynchronize inconsistent data blocks quickly.
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Parallel Resynchronization of Stale Extents With September 2007 release of HP-UX 11i v3, LVM provides new command line options to the lvextend, lvmerge,, and lvsync commands that control the synchronization of stale extents. A new option, –s, is introduced in the lvextend and lvmerge commands, which suppresses the automatic synchronization of stale extents. This synchronization can be done by using the lvsync command.
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Increased Limits Maximum Logical Volume Size Increased up to 16TB LVM in HP-UX 11i v3 release supports logical volume of sizes up to 16 terabyte (TB) (versus 2TB in earlier releases). In LVM, logical volume sizes must be a multiple of the extent size. Extent size is expressed in units of megabytes (MB) in the range of 1 to 256 and number of extents per logical volume is a decimal value in the range of 1 to 65535.
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Usability Enhancements Compact, Parsable Command Output LVM display commands have been enhanced to produce a compact and easily parsable output. A new option -F is introduced in pvdisplay, vgdisplay ,and lvdisplay commands. The commands generate colon-separated fields as key=value[,value...]:key=value[,value]. The -F option is for use in scripts. The resulting command output can be split across multiple lines. The output can include new keys or values in the future.
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my $pvdisplay_out = `pvdisplay -F $PV_NAME 2> /dev/null`; if($? != 0) { print("The PV $PV_NAME does not belong to any VG\n"); print(" Provide a PV which belong to a VG\n"); exit (1); } my @pvdisplay_pairs = split (' :', $pvdisplay_out); foreach my $key_value (@pvdisplay_pairs) { my @pair = (); @pair = split('=',$key_value); $pvdisplay_hash{$pair[0] } = $pair[1]; } print "$pvdisplay_hash{$PVDISPLAY_KEY}\n"; # get_pvinfo /dev/dsk/c11t0d5 vg_name /dev/vgtest pvdisplay – Displays user data offset and checks if
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Allocatable VGDA Cur LV PE Size (Mbytes) Total PE Free PE Allocated PE Stale PE IO Timeout (Seconds) Autoswitch Data Start Data End Boot Disk Relocated Blocks Proactive Polling yes 2 5 4 1279 779 500 0 default On 1024 34638688 no 61 On To check whether the physical volume is owned by LVM, do the following: # pvdisplay –l /dev/dsk/c4t3d0 /dev/dsk/c4t3d0:LVM_Disk=yes # pvdisplay -l /dev/disk/disk96 /dev/disk/disk96:LVM_Disk=no To find out the data start and data end of a bootable physical volume owned by LV
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With the above options, vgscan provides the following improvements: • • • With the -f option, an incorrect volume group entry in /etc/lvmtab or /etc/lvmtab_p can be corrected without modifying the rest of /etc/lvmtab or /etc/lvmtab_p. Previously, this could only be done in a cumbersome way using vgexport and vgimport to recover lvmtab or lvmtab_p entries for the root volume group.
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Couldn't stat physical volume "/dev/disk/disk27": Invalid argument Physical Volume "/dev/disk/disk36" is not part of a Volume Group Couldn't stat physical volume "/dev/disk/disk80": Invalid argument Couldn't stat physical volume "/dev/disk/disk81": Invalid argument Physical Volume "/dev/disk/disk82" is not part of a Volume Group Physical Volume "/dev/disk/disk83" is not part of a Volume Group Physical Volume "/dev/disk/disk93" is not part of a Volume Group Physical Volume "/dev/disk/disk96" contains no LVM
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/dev/disk/disk46 /dev/disk/disk47 /dev/dsk/c4t13d0 /dev/dsk/c5t13d0 /dev/dsk/c4t10d0 /dev/dsk/c5t10d0 The Volume Group /dev/vg01 was not matched with any Physical Volumes. *** LVMTAB has been created successfully. *** If PV links are configured in the system. *** Do the following to resync information on disk. *** #1. vgchange -a y *** #2. lvlnboot -R Creating "/etc/lvmtab_p".
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• • • For each physical volume, display the starting block number (KB) of the user data For each physical volume, display the PVkey (See the lvdisplay(1M) manual page for more information). For each volume group, display max_pv, max_pe, and max_lv. With the March 2008 release of HP-UX 11i v3, the –v option display the volume group version also. For a Version 2.x volume group, it also displays the maximum size to which the volume group can grow.
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# vgdisplay -v /dev/vgtest1 --- Volume groups --VG Name VG Write Access VG Status Max LV Cur LV Open LV Max PV Cur PV Act PV Max PE per PV VGDA PE Size (Mbytes) Total PE Alloc PE Free PE Total PVG Total Spare PVs Total Spare PVs in use /dev/vgtest1 read/write available, shared, server 255 1 1 16 1 1 8750 2 8 8749 50 8699 0 0 0 machine1-server machine2-client Server Client --- Logical volumes --LV Name LV Status LV Size (Mbytes) Current LE Allocated PE Used PV /dev/vgtest1/lvol1 available/syncd 400 50 5
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Max Max Max Max Max Max Max Max Max VGs LVs PVs Mirrors Stripes Stripe Size (Kbytes) LXs per LV PXs per PV Extent Size (Mbytes) 256 255 255 2 255 32768 65535 65535 256 VG Version Max VG Size (Tbytes) Max LV Size (Tbytes) Max PV Size (Tbytes) Max VGs Max LVs Max PVs Max Mirrors Max Stripes Max Stripe Size (Kbytes) Max LXs per LV Max PXs per PV Max Extent Size (Mbytes) 2.
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With the March 2008 release of HP-UX 11i v3, vgdisplay displays the volume group version, the maximum size to which the volume group can grow and the maximum number of physical extents. With the September 2008 release of HP-UX 11 iv3, LVM supports a new –V option, which displays the volume group information for all volume groups of the specified version.
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255 1 1 16 1 1 17501 2 4 17501 10 17491 0 0 0 1.0 1120064m 280016 Max LV Cur LV Open LV Max PV Cur PV Act PV Max PE per PV VGDA PE Size (Mbytes) Total PE Alloc PE Free PE Total PVG Total Spare PVs Total Spare PVs in use VG Version VG Max Size VG Max Extents For more information, see the vgdisplay(1M) manual page.
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/dev/dsk/c5t7d0 • 0 /dev/dsk/c5t7d0 4 To move extents in the range 25 to 100 from source physical volume /dev/disk/disk10 to the desired destination physical volume /dev/disk/disk22: # pvmove /dev/disk/disk10:25-100 /dev/disk/disk22 • To move the last 5 extents from /dev/disk/disk10 to another physical volume: # pvmove –e 5 /dev/disk/disk10 • To move extents to a specific location on the destination physical volume /dev/disk/disk22, starting at physical extent 50 on /dev/disk/disk22: # pvmove /dev/
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Miscellaneous Commands enhanced to prevent misconfigurations through alternate links Starting with the February 2007 release of HP-UX 11i v3, LVM commands were enhanced to avoid overwriting LVM configuration data on physical volumes that already belong to a volume group and are recorded in the /etc/lvmtab or /etc/lvmtab_p.
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Glossary 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. In other words, the device special file for a LUN remains the same even if the LUN is moved from one HBA to another, moved from one switch/hub port to another, presented via a different target port to the host, or configured with multiple hardware paths. Also referred to as persistent LUN binding.
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Volume group version Based on the metadata format, LVM supports three types of volume groups. Each type of volume group is assigned a version to distinguish from another type, based on the metadata format maintained by LVM.
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For More Information To learn more about some of the LVM features, see the following documents on HP documentation website: http://docs.hp.com (Use search with the given name of the whitepaper) http://www.docs.hp.com/en/oshpux11iv3#LVM%20Volume%20Manager • • • • • • SLVM Single-Node Online Reconfiguration (SLVM SNOR) LVM Online Disk Replacement LVM Volume Group Dynamic LUN expansion (DLE)/vgmodify LVM Volume Group Quiesce/Resume LVM Version 2.