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Bug 1255184

Summary:	cache pool conversion issues with 'cachemode'
Product:	Red Hat Enterprise Linux 7	Reporter:	Corey Marthaler <cmarthal>
Component:	lvm2	Assignee:	Zdenek Kabelac <zkabelac>
lvm2 sub component:	Cache Logical Volumes	QA Contact:	cluster-qe <cluster-qe>
Status:	CLOSED ERRATA	Docs Contact:
Severity:	high
Priority:	high	CC:	agk, heinzm, jbrassow, msnitzer, prajnoha, tlavigne, zkabelac
Version:	7.2	Keywords:	Regression, TestBlocker, Triaged
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	lvm2-2.02.129-1.el7	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-11-19 12:47:29 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 Corey Marthaler 2015-08-19 21:23:53 UTC

Description of problem:
At first I thought this had to do with specifying the cachemode when converting to cache pool, but I was also able to hit this with without specifying the cachemode at conversion time. However as soon as I ran an lvs and include a 'cachemode' in the output the "Internal error" error appears and regardless of what cachemode is supplied, whatever is in lvm.conf is what is used.




lvm2-2.02.127-1.el7.x86_64

Create origin (slow) volume
lvcreate -L 4G -n display_cache cache_sanity /dev/sdb1

Create cache data and cache metadata (fast) volumes
lvcreate -L 4G -n pool cache_sanity /dev/sde1
lvcreate -L 12M -n pool_meta cache_sanity /dev/sde1

Create cache pool volume by combining the cache data and cache metadata (fast) volumes
lvconvert --yes --type cache-pool --cachemode writeback -c 64 --poolmetadata cache_sanity/pool_meta cache_sanity/pool
  WARNING: Converting logical volume cache_sanity/pool and cache_sanity/pool_meta to pool's data and metadata volumes.
  THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)

[root@host-115 ~]# lvs -a -o +devices,cachemode
  LV              Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices         Cachemode
  display_cache   -wi-a-----   4.00g                                                     /dev/sdb1(0)             
  [lvol0_pmspare] ewi-------  12.00m                                                     /dev/sdc1(0)             
  pool            Cwi---C---   4.00g                                                     pool_cdata(0)   writeback
  [pool_cdata]    Cwi-------   4.00g                                                     /dev/sde1(0)             
  [pool_cmeta]    ewi-------  12.00m                                                     /dev/sde1(1024)          

[root@host-115 ~]# lvs --noheadings -o lv_name --select 'cachemode=writeback'
  pool




lvm2-2.02.128-1.el7.x86_64

Create origin (slow) volume
lvcreate -L 4G -n display_cache cache_sanity /dev/sde1

Create cache data and cache metadata (fast) volumes
lvcreate -L 4G -n pool cache_sanity /dev/sdd1
lvcreate -L 12M -n pool_meta cache_sanity /dev/sdd1

Create cache pool volume by combining the cache data and cache metadata (fast) volumes
lvconvert --yes --type cache-pool --cachemode writeback -c 32 --poolmetadata cache_sanity/pool_meta cache_sanity/pool
  WARNING: Converting logical volume cache_sanity/pool and cache_sanity/pool_meta to pool's data and metadata volumes.
  THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)

# Where did the pool volume go?
[root@host-109 ~]# lvs -a -o +devices,cachemode
  Internal error: LV cache_sanity/pool has uknown feature flags 0.
  _do_report_object: report function failed for field cachemode
  LV              Attr       LSize   Pool Origin Data%  Meta%   Cpy%Sync Devices         Cachemode
  display_cache   -wi-a-----   4.00g                                     /dev/sde1(0)             
  [lvol0_pmspare] ewi-------  12.00m                                     /dev/sdc1(0)             
  [pool_cdata]    Cwi-------   4.00g                                     /dev/sdd1(0)             
  [pool_cmeta]    ewi-------  12.00m                                     /dev/sdd1(1024)          

[root@host-109 ~]# lvs --noheadings -o lv_name --select 'cachemode=writeback'
  Internal error: LV cache_sanity/pool has uknown feature flags 0.
  _do_report_object: report function failed for field cachemode

[root@host-109 ~]#  lvconvert --yes --type cache --cachepool cache_sanity/pool cache_sanity/display_cache
  Logical volume cache_sanity/display_cache is now cached.

[root@host-109 ~]# lvs --noheadings -o lv_name --select 'cachemode=writeback'
[root@host-109 ~]# dmsetup status
cache_sanity-display_cache: 0 8388608 cache 8 135/3072 128 0/65536 0 61 0 0 0 0 0 1 writethrough 2 migration_threshold 2048 smq 0 rw - 

[root@host-109 ~]# lvs -a -o +devices,cachemode
  LV                    Attr       LSize   Pool   Origin                Data%  Meta%   Cpy%Sync Devices                Cachemode   
  display_cache         Cwi-a-C---   4.00g [pool] [display_cache_corig] 0.00   4.39    100.00   display_cache_corig(0) writethrough
  [display_cache_corig] owi-aoC---   4.00g                                                      /dev/sdd1(0)                       
  [lvol0_pmspare]       ewi-------  12.00m                                                      /dev/sdc1(0)                       
  [pool]                Cwi---C---   4.00g                              0.00   4.39    100.00   pool_cdata(0)          writethrough
  [pool_cdata]          Cwi-ao----   4.00g                                                      /dev/sde1(0)                       
  [pool_cmeta]          ewi-ao----  12.00m                                                      /dev/sde1(1024)

Comment 1 Zdenek Kabelac 2015-08-20 09:26:09 UTC

All cache attributes are now primarily entered when LV is cached - cache-pool should be seen as 'wrapper' for Data & Metadata LV  (building brick).

However for backward compatibility we fully support also cache-pool with all caching attributes set - so of course this bug needs couple fixes.

However it's now valid unused cache-pool is now without any cache-mode set - this setting will be taken from configuration just in the moment you attach cache-pool to some LV.

Currently the only setting which is set when cache-pool is created is cache-pool chunk size - which is needs for estimation of cache-pool metadata volume size.

Comment 3 Zdenek Kabelac 2015-08-26 11:46:33 UTC

Addressed with upstream commit:

https://www.redhat.com/archives/lvm-devel/2015-August/msg00185.html

Comment 6 Corey Marthaler 2015-09-02 21:00:12 UTC

Fix verified in the latest rpms.

3.10.0-313.el7.x86_64
lvm2-2.02.129-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
lvm2-libs-2.02.129-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
lvm2-cluster-2.02.129-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
device-mapper-1.02.106-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
device-mapper-libs-1.02.106-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
device-mapper-event-1.02.106-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
device-mapper-event-libs-1.02.106-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
device-mapper-persistent-data-0.5.5-1.el7    BUILT: Thu Aug 13 09:58:10 CDT 2015
cmirror-2.02.129-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015
sanlock-3.2.4-1.el7    BUILT: Fri Jun 19 12:48:49 CDT 2015
sanlock-lib-3.2.4-1.el7    BUILT: Fri Jun 19 12:48:49 CDT 2015
lvm2-lockd-2.02.129-2.el7    BUILT: Wed Sep  2 02:51:56 CDT 2015



[root@host-109 ~]# grep writethrough /etc/lvm/lvm.conf
        # Possible options are: writethrough, writeback.
        # writethrough - Data blocks are immediately written from
        cache_pool_cachemode = "writethrough"


[root@host-109 ~]# vgcreate cache_sanity /dev/sd[abcdefgh]1
  Volume group "cache_sanity" successfully created
[root@host-109 ~]# lvcreate -L 4G -n display_cache cache_sanity /dev/sde1
  Logical volume "display_cache" created.
[root@host-109 ~]# lvcreate -L 4G -n pool cache_sanity /dev/sdd1
  Logical volume "pool" created.
[root@host-109 ~]# lvcreate -L 12M -n pool_meta cache_sanity /dev/sdd1
  Logical volume "pool_meta" created.
[root@host-109 ~]# lvconvert --yes --type cache-pool --cachemode writeback -c 32 --poolmetadata cache_sanity/pool_meta cache_sanity/pool
  WARNING: Converting logical volume cache_sanity/pool and cache_sanity/pool_meta to pool's data and metadata volumes.
  THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)
  Converted cache_sanity/pool to cache pool.
[root@host-109 ~]# lvs -a -o +devices,cachemode
  LV              VG            Attr       LSize   Pool Origin Data%  Meta% Cpy%Sync Devices         Cachemode
  display_cache   cache_sanity  -wi-a-----   4.00g                                   /dev/sde1(0)
  [lvol0_pmspare] cache_sanity  ewi-------  12.00m                                   /dev/sda1(0)
  pool            cache_sanity  Cwi---C---   4.00g                                   pool_cdata(0)   writeback
  [pool_cdata]    cache_sanity  Cwi-------   4.00g                                   /dev/sdd1(0)
  [pool_cmeta]    cache_sanity  ewi-------  12.00m                                   /dev/sdd1(1024)

[root@host-109 ~]# lvs --noheadings -o lv_name --select 'cachemode=writeback'
  pool
[root@host-109 ~]# lvconvert --yes --type cache --cachepool cache_sanity/pool cache_sanity/display_cache
  Logical volume cache_sanity/display_cache is now cached.
[root@host-109 ~]# lvs --noheadings -o lv_name --select 'cachemode=writeback'
  display_cache

[root@host-109 ~]# dmsetup status
cache_sanity-display_cache: 0 8388608 cache 8 266/3072 64 3/131072 6 64 0 0 0 3 0 1 writeback 2 migration_threshold 2048 smq 0 rw - 

[root@host-109 ~]# lvs -a -o +devices,cachemode
  LV                    VG            Attr       LSize Pool   Origin                Data%  Meta% Cpy%Sync Devices                Cachemode
  display_cache         cache_sanity  Cwi-a-C--- 4.00g [pool] [display_cache_corig] 0.00   8.66  0.00     display_cache_corig(0) writeback
  [display_cache_corig] cache_sanity  owi-aoC--- 4.00g                                                    /dev/sde1(0)
  [lvol0_pmspare]       cache_sanity  ewi------- 12.00m                                                   /dev/sda1(0)
  [pool]                cache_sanity  Cwi---C--- 4.00g                              0.00   8.66  0.00     pool_cdata(0)          writeback
  [pool_cdata]          cache_sanity  Cwi-ao---- 4.00g                                                    /dev/sdd1(0)
  [pool_cmeta]          cache_sanity  ewi-ao---- 12.00m                                                   /dev/sdd1(1024)

Comment 7 errata-xmlrpc 2015-11-19 12:47:29 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-2015-2147.html