Bug 1436748 - LVM Cache: Be ready to consume cache metadata V2
Summary: LVM Cache: Be ready to consume cache metadata V2
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: 1393566
TreeView+ depends on / blocked
Reported: 2017-03-28 14:35 UTC by Jonathan Earl Brassow
Modified: 2021-09-03 12:51 UTC (History)
12 users (show)

Fixed In Version: lvm2-2.02.169-3.el7
Doc Type: Release Note
Doc Text:
LVM now supports dm-cache metadata version 2 LVM/DM cache has been significantly improved. It provides support for larger cache sizes, better adaptation to changing workloads, greatly improved startup and shutdown times, and higher performance overall. Version 2 of the dm-cache metadata format is now the default when creating cache logical volumes with LVM. Version 1 will continue to be supported for previously created LVM cache logical volumes. Upgrading to version 2 will require the removal of the old cache layer and the creation of a new cache layer.
Clone Of: 1393566
Last Closed: 2017-08-01 21:49:49 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
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 2017-03-28 14:35:31 UTC
+++ This bug was initially created as a clone of Bug #1393566 +++

The on-disk metadata used by dm-cache is being updated to allow for performance enhancements.  LVM will need to pass down additional DM table arguments in order to activate these changes.  We need to have a solution ready that is forward/backwards compatible.

--- Additional comment from Zdenek Kabelac on 2017-02-20 05:09:06 EST ---

So lets list the options:

lvm2 new parameter:

1.) --cacheversion   1|2|auto

2.) --cache-metadata-version 2 ?

3.) --metadata-version 2  ?

4.) --cacheformat   1|2|auto    (or maybe this: v1|v2|auto ) ?


libdm API options:

1.) add new dm_tree_node_set_cache_version(....) 
2.) add new dm_tree_node_set_cache_format(....) 



ATM I'd prefer the format to be automatically recognized by the 'cache_check' tool - as adding some 'magical' args by lvm2 to the existing configurable set can be problematic for a user - it could be done - but lvm2 will be changing passed option set.

i.e. it's then unclear if we should use:

cache_check  --metadata-version 2

and also

cache_check  --metadata-version 1

or just use it with version 2 ?


Waiting for more judgment here.

Comment 5 Steven J. Levine 2017-05-17 17:46:00 UTC

Should we have a release note writeup fo this feature?


Comment 6 Corey Marthaler 2017-06-22 22:08:37 UTC
Marking this feature verified in the latest rpms.

All current cache scenarios passed with both  --cachemetadataformat 2 and 1, as well as attempted activation on older (7.3,7.2) versions. See bug 1451459 for more information on up|downgrade testing.	

lvm2-2.02.171-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
lvm2-libs-2.02.171-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
lvm2-cluster-2.02.171-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
device-mapper-1.02.140-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
device-mapper-libs-1.02.140-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
device-mapper-event-1.02.140-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
device-mapper-event-libs-1.02.140-7.el7    BUILT: Thu Jun 22 08:35:15 CDT 2017
device-mapper-persistent-data-0.7.0-0.1.rc6.el7    BUILT: Mon Mar 27 10:15:46 CDT 2017

Comment 7 errata-xmlrpc 2017-08-01 21:49:49 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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