1592490 – cache metadata format no longer honored

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Bug 1592490 - cache metadata format no longer honored

Summary: cache metadata format no longer honored

Keywords:
Status:	CLOSED ERRATA
Alias:	None
Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	lvm2
Sub Component:
Version:	7.6
Hardware:	x86_64
OS:	Linux
Priority:	unspecified
Severity:	medium
Target Milestone:	rc
Target Release:	---
Assignee:	Zdenek Kabelac
QA Contact:	cluster-qe@redhat.com
Docs Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+	depends on / blocked

Reported:	2018-06-18 16:13 UTC by Corey Marthaler
Modified:	2021-09-03 12:50 UTC (History)
CC List:	7 users (show)
Fixed In Version:	lvm2-2.02.180-4.el7
Doc Type:	If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:	2018-10-30 11:03:47 UTC
Target Upstream Version:
Embargoed:

Attachments	(Terms of Use)

Links
System	ID	Private	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHBA-2018:3193	0	None	None	None	2018-10-30 11:04:28 UTC

Description Corey Marthaler 2018-06-18 16:13:25 UTC

Description of problem:

[root@host-086 ~]# pvs -a -o +pv_tags
  PV          VG            Fmt  Attr PSize   PFree   PV Tags
  /dev/sda1                      ---       0       0         
  /dev/sdb1   cache_sanity  lvm2 a--  <24.99g <24.99g        
  /dev/sdc1   cache_sanity  lvm2 a--  <24.99g <24.99g fast   
  /dev/sdd1                      ---       0       0         
  /dev/sde1                      ---       0       0         
  /dev/sdf1   cache_sanity  lvm2 a--  <24.99g <24.99g slow   
  /dev/sdg1                      ---       0       0         
  /dev/sdh1   cache_sanity  lvm2 a--  <24.99g <24.99g        
  /dev/sdi1                      ---       0       0         

[root@host-086 ~]# lvcreate --wipesignatures y  -L 4G -n corigin cache_sanity @slow
  Logical volume "corigin" created.
[root@host-086 ~]# lvcreate  -L 2G -n cache_then_deactivate_pool cache_sanity @fast
  Logical volume "cache_then_deactivate_pool" created.
[root@host-086 ~]# lvcreate  -L 12M -n cache_then_deactivate_pool_meta cache_sanity @fast
  Logical volume "cache_then_deactivate_pool_meta" created.

[root@host-086 ~]# lvconvert --yes --type cache-pool --cachepolicy mq --cachemode writeback -c 64 --poolmetadata cache_sanity/cache_then_deactivate_pool_meta cache_sanity/cache_then_deactivate_pool
  WARNING: Converting cache_sanity/cache_then_deactivate_pool and cache_sanity/cache_then_deactivate_pool_meta to cache pool's data and metadata volumes with metadata wiping.
  THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)
  Converted cache_sanity/cache_then_deactivate_pool and cache_sanity/cache_then_deactivate_pool_meta to cache pool.
[root@host-086 ~]# lvconvert --yes --type cache --cachemetadataformat 2 --cachepool cache_sanity/cache_then_deactivate_pool cache_sanity/corigin
  Logical volume cache_sanity/corigin is now cached.

# lvm cache metadata format doesn't appear to be consistent with what was specified (2)

[root@host-086 ~]# lvs -a -o +cachemetadataformat
  LV                                 VG            Attr       LSize   Pool                         Origin          Data%  Meta%  Move Log Cpy%Sync Convert CMFmt
  [cache_then_deactivate_pool]       cache_sanity  Cwi---C---   2.00g                                              0.03   2.38            0.00                 1
  [cache_then_deactivate_pool_cdata] cache_sanity  Cwi-ao----   2.00g                                                                                           
  [cache_then_deactivate_pool_cmeta] cache_sanity  ewi-ao----  12.00m                                                                                           
  corigin                            cache_sanity  Cwi-a-C---   4.00g [cache_then_deactivate_pool] [corigin_corig] 0.03   2.38            0.00                 1
  [corigin_corig]                    cache_sanity  owi-aoC---   4.00g                                                                                           
  [lvol0_pmspare]                    cache_sanity  ewi-------  12.00m                                                                                                                                                                      


Version-Release number of selected component (if applicable):
3.10.0-906.el7.x86_64

lvm2-2.02.179-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
lvm2-libs-2.02.179-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
lvm2-cluster-2.02.179-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
lvm2-lockd-2.02.179-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
lvm2-python-boom-0.8.5-6.el7    BUILT: Mon Jun 18 01:16:13 CDT 2018
cmirror-2.02.179-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
device-mapper-1.02.148-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
device-mapper-libs-1.02.148-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
device-mapper-event-1.02.148-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
device-mapper-event-libs-1.02.148-1.el7    BUILT: Mon Jun 18 01:12:41 CDT 2018
device-mapper-persistent-data-0.7.3-3.el7    BUILT: Tue Nov 14 05:07:18 CST 2017


How reproducible:
Everytime

Comment 3 Zdenek Kabelac 2018-06-22 13:16:05 UTC

MQ policy is the old one - not upgraded to format 2.

Users are supposed to use SMQ policy.

The kernel handles  MQ via  alias to SMQ - but in lvm2 terminology - we keep the name historical and associated with format 1 (kernel also ignores any  MQ related parameters - so the alias is not a 'fair' match - as SMQ works slightly differently.

So ATM it this works as designed, unless I'd be convinced we want to support creation of caches with MQ policy and format 2.

Comment 4 Corey Marthaler 2018-06-22 19:13:23 UTC

Why the change in behavior all of a sudden, and should it be documented? This has been allowed in all prior versions of rhel7 and now changes in 7.6.

### RHEL7.5

# Create origin (slow) volume
lvcreate --wipesignatures y --activate ey -L 4G -n display_cache cache_sanity @slow

# Create cache data and cache metadata (fast) volumes
lvcreate --activate ey -L 4G -n pool cache_sanity @fast
lvcreate --activate ey -L 12M -n pool_meta cache_sanity @fast

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

# Create cached volume by combining the cache pool (fast) and origin (slow) volumes
lvconvert --yes --type cache --cachemetadataformat 2 --cachepool cache_sanity/pool cache_sanity/display_cache

[root@harding-02 ~]# lvs -a -o +devices,cachepolicy,cachemetadataformat
 LV                    VG            Attr       LSize    Pool   Origin                Data%  Meta% Cpy%Sync Devices                   CachePolicy CMFmt
 display_cache         cache_sanity  Cwi-a-C---    4.00g [pool] [display_cache_corig] 0.00   8.95  0.00     display_cache_corig(0)    mq              2
 [display_cache_corig] cache_sanity  owi-aoC---    4.00g                                                    /dev/mapper/mpathe1(0)
 [lvol0_pmspare]       cache_sanity  ewi-------   12.00m                                                    /dev/mapper/mpatha1(1027)
 [pool]                cache_sanity  Cwi---C---    4.00g                              0.00   8.95  0.00     pool_cdata(0)             mq              2
 [pool_cdata]          cache_sanity  Cwi-ao----    4.00g                                                    /dev/mapper/mpatha1(0)
 [pool_cmeta]          cache_sanity  ewi-ao----   12.00m                                                    /dev/mapper/mpatha1(1024)

[root@harding-02 ~]# dmsetup status | grep cache_sanity-display_cache:
cache_sanity-display_cache: 0 8388608 cache 8 272/3072 64 0/131072 0 64 0 0 0 0 0 2 metadata2 writethrough 2 migration_threshold 2048 mq 10 random_threshold 0 sequential_threshold 0 discard_promote_adjustment 0 read_promote_adjustment 0 write_promote_adjustment 0 rw - 




### RHEL7.6

# Create origin (slow) volume
lvcreate --wipesignatures y  -L 4G -n display_cache cache_sanity @slow

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

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

# Create cached volume by combining the cache pool (fast) and origin (slow) volumes
lvconvert --yes --type cache --cachemetadataformat 2 --cachepool cache_sanity/pool cache_sanity/display_cache

[root@host-086 ~]#  lvs -a -o +devices,cachepolicy,cachemetadataformat
 LV                    VG            Attr       LSize   Pool   Origin                Data%  Meta% Cpy%Sync Devices                CachePolicy CMFmt
 display_cache         cache_sanity  Cwi-a-C---   4.00g [pool] [display_cache_corig] 0.00   4.46  0.00     display_cache_corig(0) mq              1
 [display_cache_corig] cache_sanity  owi-aoC---   4.00g                                                    /dev/sdc1(0)
 [lvol0_pmspare]       cache_sanity  ewi-------  12.00m                                                    /dev/sdb1(1027)
 [pool]                cache_sanity  Cwi---C---   4.00g                              0.00   4.46  0.00     pool_cdata(0)          mq              1
 [pool_cdata]          cache_sanity  Cwi-ao----   4.00g                                                    /dev/sdb1(0)
 [pool_cmeta]          cache_sanity  ewi-ao----  12.00m                                                    /dev/sdb1(1024)

[root@host-086 ~]# dmsetup status | grep cache_sanity-display_cache:
cache_sanity-display_cache: 0 8388608 cache 8 135/3072 128 0/65536 0 49 0 0 0 0 0 1 writethrough 2 migration_threshold 2048 mq 10 random_threshold 0 sequential_threshold 0 discard_promote_adjustment 0 read_promote_adjustment 0 write_promote_adjustment 0 rw -

Comment 5 Zdenek Kabelac 2018-06-22 19:35:46 UTC

hmmm so this rather bug has leaked already into 7.5 - where it was catching to support format2 - so not all validation was in place.

But in that case we may possibly need to preserve this logic - it's just one extra if case - so not big issue really.

I'll take closer look what would be the impact - we could consider  'format2' as having higher precedence then oldish  'mq' policy.

Comment 6 Zdenek Kabelac 2018-08-07 22:41:22 UTC

Dropped connection between policy and format - so it can be set independently.

https://www.redhat.com/archives/lvm-devel/2018-August/msg00013.html

Comment 8 Corey Marthaler 2018-08-24 21:04:54 UTC

Fix verified in the latest rpms.

3.10.0-937.el7.x86_64
lvm2-2.02.180-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
lvm2-libs-2.02.180-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
lvm2-cluster-2.02.180-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
lvm2-lockd-2.02.180-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
lvm2-python-boom-0.9-8.el7    BUILT: Tue Aug 21 11:28:32 CDT 2018
cmirror-2.02.180-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
device-mapper-1.02.149-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
device-mapper-libs-1.02.149-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
device-mapper-event-1.02.149-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
device-mapper-event-libs-1.02.149-5.el7    BUILT: Tue Aug 21 11:29:37 CDT 2018
device-mapper-persistent-data-0.7.3-3.el7    BUILT: Tue Nov 14 05:07:18 CST 2017



[root@hayes-01 ~]# lvcreate --wipesignatures y  -L 4G -n corigin cache_sanity /dev/sdb1
  Logical volume "corigin" created.
[root@hayes-01 ~]# lvcreate  -L 2G -n cache_then_deactivate_pool cache_sanity /dev/sdc1
  Logical volume "cache_then_deactivate_pool" created.
[root@hayes-01 ~]# lvcreate  -L 12M -n cache_then_deactivate_pool_meta cache_sanity /dev/sdc1
  Logical volume "cache_then_deactivate_pool_meta" created.

[root@hayes-01 ~]# lvconvert --yes --type cache-pool --cachepolicy mq --cachemode writeback -c 64 --poolmetadata cache_sanity/cache_then_deactivate_pool_meta cache_sanity/cache_then_deactivate_pool
  WARNING: Converting cache_sanity/cache_then_deactivate_pool and cache_sanity/cache_then_deactivate_pool_meta to cache pool's data and metadata volumes with metadata wiping.
  THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)
  Converted cache_sanity/cache_then_deactivate_pool and cache_sanity/cache_then_deactivate_pool_meta to cache pool.
[root@hayes-01 ~]# lvconvert --yes --type cache --cachemetadataformat 2 --cachepool cache_sanity/cache_then_deactivate_pool cache_sanity/corigin
  Logical volume cache_sanity/corigin is now cached.

[root@hayes-01 ~]# lvs -a -o +cachemetadataformat
  LV                                 Attr       LSize  Pool                         Origin          Data% Meta%   Cpy%Sync CMFmt
  [cache_then_deactivate_pool]       Cwi---C---  2.00g                                              0.03  2.51    0.00         2
  [cache_then_deactivate_pool_cdata] Cwi-ao----  2.00g
  [cache_then_deactivate_pool_cmeta] ewi-ao---- 12.00m
  corigin                            Cwi-a-C---  4.00g [cache_then_deactivate_pool] [corigin_corig] 0.03  2.51    0.00         2
  [corigin_corig]                    owi-aoC---  4.00g
  [lvol0_pmspare]                    ewi------- 12.00m

Comment 10 errata-xmlrpc 2018-10-30 11:03:47 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://access.redhat.com/errata/RHBA-2018:3193

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