Bug 1189108 - LVM Cache: Ability to create thinsnap of cached external origin
Summary: LVM Cache: Ability to create thinsnap of cached external origin
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: lvm2
Version: 7.2
Hardware: Unspecified
OS: Unspecified
Target Milestone: rc
: ---
Assignee: Zdenek Kabelac
QA Contact: cluster-qe@redhat.com
Steven J. Levine
Depends On:
Blocks: 1385242 1471212
TreeView+ depends on / blocked
Reported: 2015-02-04 13:23 UTC by Jonathan Earl Brassow
Modified: 2021-09-03 12:50 UTC (History)
13 users (show)

Fixed In Version: lvm2-2.02.169-1.el7
Doc Type: Release Note
Doc Text:
Support for thin snapshots of cached logical volumes LVM in Red Hat Enterprise Linux 7.4 allows you to create thin snapshots of cached logical volumes. This feature was not available in earlier releases. These external origin cached logical volumes are converted to a read-only state and thus can be used by different thin pools.
Clone Of:
: 1471212 (view as bug list)
Last Closed: 2017-08-01 21:47:18 UTC
Target Upstream Version:

Attachments (Terms of Use)
test result (30.78 KB, text/plain)
2017-04-10 09:32 UTC, Roman Bednář
no flags Details

System ID Private Priority Status Summary Last Updated
Red Hat Knowledge Base (Solution) 1428303 0 None None None Never
Red Hat Product Errata RHBA-2017:2222 0 normal SHIPPED_LIVE lvm2 bug fix and enhancement update 2017-08-01 18:42:41 UTC

Description Jonathan Earl Brassow 2015-02-04 13:23:57 UTC
Add ability to create thinsnap of cached external origin

Comment 10 Zdenek Kabelac 2016-12-19 15:44:35 UTC
Upstream patch (member of 2.02.169 release)


enabled support for using cache LV as external origin (together with surrounding patches to unable online caching & uncaching of existing external origin).

Also (as it's using very similar dm tree handling) we enabled usage for  'old' snapshot of cache LV.

Basically there is no extension to supported syntax, just accepts 'cache' type as accepted LV type for command.

lvconvert --thin vg/cacheLV --originname extorigname --thinpool vg/pool

- makes cacheLV -> cached external origin (read-only) and  thinLV available to the user for read/write

lvcreate -s  -L1 vg/cacheLV

- takes snapshot of cached LV which could be later dropped/merged

lvconvert -s vg/cacheLV  cowLV

- recombine i.e. split snapshot back together with cached origin.

Comment 13 Roman Bednář 2017-04-10 09:32:59 UTC
Created attachment 1270433 [details]
test result

Verified. It is now possible to use cacheLV as external origin for thin snapshot. 

Also added automated test coverage. External cache origin test will be now part of regression testing as well. Ext. cache variants also available for other scenarios which used non-cached ext. origin up until now.

Attaching test result logs for single node and cluster tests.
Unique test name for test execution via vedder added to QA whiteboard for reference.


lvm2-2.02.169-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
lvm2-libs-2.02.169-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
lvm2-cluster-2.02.169-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
device-mapper-1.02.138-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
device-mapper-libs-1.02.138-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
device-mapper-event-1.02.138-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
device-mapper-event-libs-1.02.138-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017
device-mapper-persistent-data-0.7.0-0.1.rc6.el7    BUILT: Mon Mar 27 17:15:46 CEST 2017
cmirror-2.02.169-3.el7    BUILT: Wed Mar 29 16:17:46 CEST 2017

Comment 15 Steven J. Levine 2017-07-14 17:08:46 UTC
Adding summary for release note format, plus very slight edit of release note text.

Comment 16 errata-xmlrpc 2017-08-01 21:47:18 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.


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