Patch Name: PHKL_30686

Patch Description: s700_800 11.23 LVM chooses metadata in incorrect PV

Creation Date: 04/07/06

Post Date: 04/07/12

Repost: 04/07/13 
	The patch documentation was modified to more fully document
	the logic of the defective behavior described in the second
	paragraph of the Defect Description. 

Hardware Platforms - OS Releases:
	s700: 11.23
	s800: 11.23

Products: N/A

Filesets:
	LVM.LVM-KRN,fr=B.11.23,fa=HP-UX_B.11.23_IA,v=HP

Automatic Reboot?: Yes

Status: General Release

Critical:
	Yes
	PHKL_30686: CORRUPTION

Category Tags:
	defect_repair general_release critical corruption

Path Name: /hp-ux_patches/s700_800/11.X/PHKL_30686

Symptoms:
	PHKL_30686:
	( SR:8606359992 CR:JAGaf20688 )
	In 11.23 only, under certain scenarios involving mirrored
	logical volumes in IA systems, there is a data integrity
	risk when

	- the activation of the volume group (which include mirrored
	  logical volumes) is done with a PV that was missing at the
	  time of the the previous deactivation.

	- in an SLVM cluster, a client becomes the server after a
	  missing PV which was part of a mirrored logical volume has
	  come back online.

	The problem can only occur if the PV (or PVs) involved is
	listed first in the /etc/lvmtab file.

Defect Description:
	PHKL_30686:
	( SR:8606359992 CR:JAGaf20688 )
	When a volume group is activated, or when a client becomes a
	server in an SLVM cluster, LVM searches the physical volumes
	in the volume group for the latest copy of the LVM metadata.
	On IA systems in 11.23, there's the possibility that LVM
	will pick the wrong copy of the metadata.

	LVM searches the physical volumes comprising the logical
	volume to determine which has the most recent metadata.
	Because of this defect, LVM might continue to consider the
	metadata on the physical volume with the lowest pvkey (see
	lvdisplay(1M)) as the latest, even if this is not correct.

	For example, assume we have a volume group with two physical
	volumes (PV1 and PV2) and a single mirrored logical volume
	(LV1) with a mirror on each of the two physical volumes. As
	long as both physical volumes are available, the metadata on
	both will be up to date and there is no problem.

	Now, assume that PV1 becomes unavailable. As I/O is done to
	LV1, extents on PV1 become stale and the metadata on PV2 is
	updated to reflect the new states of the extents.

	Next, the volume group is deactivated. At this point the
	metadata on PV1 shows all extents current, and the metadata
	on PV2 indicates that some extents on PV1 are stale. Now,
	the volume is activated with both PV1 and PV2 available.

	LVM will incorrectly choose the metadata on PV1 instead of
	the more recent metadata on PV2. Since the PV1 metadata
	shows that all extents are current, there will be no
	resync. This leaves the logical volume in an incorrect
	state in that some of the extents have different data on
	the two mirrors.

	Resolution:
	The code has now been restructured to ensure that the
	correct copy of the metadata is always chosen.

Enhancement:
	No

SR:
	8606359992

Patch Files:
	
	LVM.LVM-KRN,fr=B.11.23,fa=HP-UX_B.11.23_IA,v=HP:
	/usr/conf/lib/liblvm.a(lv_quorum.o)

what(1) Output:
	
	LVM.LVM-KRN,fr=B.11.23,fa=HP-UX_B.11.23_IA,v=HP:
	/usr/conf/lib/liblvm.a(lv_quorum.o):
		lv_quorum.c $Date: 2004/06/25 10:53:36 $Revision: r1
			1.23/1 PATCH_11.23 (PHKL_30686)

cksum(1) Output:
	
	LVM.LVM-KRN,fr=B.11.23,fa=HP-UX_B.11.23_IA,v=HP:
	1937021231 119464 /usr/conf/lib/liblvm.a(lv_quorum.o)

Patch Conflicts: None

Patch Dependencies: None

Hardware Dependencies: None

Other Dependencies: None

Supersedes: None

Equivalent Patches: None

Patch Package Size: 60 KBytes

Installation Instructions:
	Please review all instructions and the Hewlett-Packard
	SupportLine User Guide or your Hewlett-Packard support terms
	and conditions for precautions, scope of license,
	restrictions, and, limitation of liability and warranties,
	before installing this patch.
	------------------------------------------------------------
	1. Back up your system before installing a patch.

	2. Login as root.

	3. Copy the patch to the /tmp directory.

	4. Move to the /tmp directory and unshar the patch:

		cd /tmp
		sh PHKL_30686

	5. Run swinstall to install the patch:

		swinstall -x autoreboot=true -x patch_match_target=true \
			  -s /tmp/PHKL_30686.depot

	By default swinstall will archive the original software in 
	/var/adm/sw/save/PHKL_30686.  If you do not wish to retain a
	copy of the original software, include the patch_save_files
	option in the swinstall command above:

		-x patch_save_files=false

	WARNING: If patch_save_files is false when a patch is installed,
		 the patch cannot be deinstalled.  Please be careful
		 when using this feature.

	For future reference, the contents of the PHKL_30686.text file is 
	available in the product readme:

		swlist -l product -a readme -d @ /tmp/PHKL_30686.depot

	To put this patch on a magnetic tape and install from the
	tape drive, use the command:

		dd if=/tmp/PHKL_30686.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions: None