Bug 1202916

Summary: LVM Cache: Full Support
Product: Red Hat Enterprise Linux 6 Reporter: Jonathan Earl Brassow <jbrassow>
Component: lvm2Assignee: Jonathan Earl Brassow <jbrassow>
lvm2 sub component: Cache Logical Volumes (RHEL6) QA Contact: cluster-qe <cluster-qe>
Status: CLOSED ERRATA Docs Contact:
Severity: unspecified    
Priority: unspecified CC: agk, cmarthal, heinzm, jbrassow, msnitzer, prajnoha, zkabelac
Version: 6.7   
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
⁠LVM Cache As of Red Hat Enterprise Linux 6.7, LVM cache is fully supported. This feature allows users to create logical volumes (LVs) with a small fast device performing as a cache to larger slower devices. Refer to the lvmcache(7) manual page for information on creating cache logical volumes. Note the following restrictions on the use of cache LVs: - The cache LV must be a top-level device. It cannot be used as a thin-pool LV, an image of a RAID LV, or any other sub-LV type. - The cache LV sub-LVs (the origin LV, metadata LV, and data LV) can only be of linear, stripe, or RAID type. - The properties of the cache LV cannot be changed after creation. To change cache properties, remove the cache as described in lvmcache(7) and recreate it with the desired properties.
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-07-22 07:38:26 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Jonathan Earl Brassow 2015-03-17 17:00:17 UTC
LVM cache will be supported in RHEL6.7.  The feature is already in position, but we need release notes stating this.

Comment 2 Corey Marthaler 2015-06-12 21:48:48 UTC
QA has verified the the following items required for "full support" in RHEL6.7.

1. The ability to create, remove, report on cache LVs created on top of linear, stripe or RAID LVs.
2. The cache LV components (data and metadata sub-LVs) can be linear, stripe or RAID LVs.
3. The user will be able to select the cache mode (either writeback or writethrough).
   (This does not mean they will be able to switch cachemode while the cache is in-use)
4. The user will be able to select the granularity of cache chunks (i.e. chunk size).
5. Cache size, mode, and policy cannot be changed after creation.


Currently open 6.7 bugs from QA cache test cases:
1216214 - "attempt to access beyond end of device" when attempting a raid cache pool on 1k extent VG
1114113 - OOM issues when caching many volumes
1113770 - need a more graceful way to fail when attempting to cache RO devices


2.6.32-563.el6.x86_64
lvm2-2.02.118-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
lvm2-libs-2.02.118-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
lvm2-cluster-2.02.118-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
udev-147-2.62.el6    BUILT: Thu Apr 23 05:44:37 CDT 2015
device-mapper-1.02.95-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
device-mapper-libs-1.02.95-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
device-mapper-event-1.02.95-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
device-mapper-event-libs-1.02.95-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015
device-mapper-persistent-data-0.3.2-1.el6    BUILT: Fri Apr  4 08:43:06 CDT 2014
cmirror-2.02.118-2.el6    BUILT: Wed Apr 15 06:34:08 CDT 2015

Comment 3 errata-xmlrpc 2015-07-22 07:38:26 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-1411.html