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Bug 1458006

Summary: RAID TAKEOVER: lvm should choose direct path to desired raid level
Product: Red Hat Enterprise Linux 7 Reporter: Corey Marthaler <cmarthal>
Component: lvm2Assignee: Heinz Mauelshagen <heinzm>
lvm2 sub component: Mirroring and RAID QA Contact: cluster-qe <cluster-qe>
Status: CLOSED CURRENTRELEASE Docs Contact:
Severity: unspecified    
Priority: unspecified CC: agk, heinzm, jbrassow, msnitzer, prajnoha, prockai, zkabelac
Version: 7.4   
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: 2.02.172 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1468600 (view as bug list) Environment:
Last Closed: 2017-08-18 11:21:33 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:
Bug Depends On:    
Bug Blocks: 1468600    

Description Corey Marthaler 2017-06-01 18:14:55 UTC 
Description of problem:
Found this while testing the new expected behavior for bug 1439403. Originally, lvm was going to fail on any none direct raid takeover paths and give the user current possible options. However, that appears to have changed now in the latest rpms (171-3), and is now going to attempt the first step towards the desired raid level. With that in mind, lvm should be choosing the most direct route.


### raid4 -> 10 manually (2 steps)
[root@host-128 ~]# lvcreate  --type raid4 -i 3 -n LV -L 500M VG
  Using default stripesize 64.00 KiB.
  Rounding size 500.00 MiB (125 extents) up to stripe boundary size 504.00 MiB(126 extents).
  Logical volume "LV" created.

[root@host-128 ~]# lvconvert --type raid0_meta VG/LV
  Using default stripesize 64.00 KiB.
Are you sure you want to convert raid4 LV VG/LV to raid0_meta type? [y/n]: y
  Logical volume VG/LV successfully converted.

# No need to wait for sync to complete either

[root@host-128 ~]# lvconvert --type raid10 VG/LV
  Using default stripesize 64.00 KiB.
Are you sure you want to convert raid0_meta LV VG/LV to raid10 type? [y/n]: y
  Logical volume VG/LV successfully converted.




### raid4 -> 10 letting lvm decide (3 steps and a wait for sync to complete)
[root@host-128 ~]# lvcreate  --type raid4 -i 3 -n LV -L 500M VG
  Using default stripesize 64.00 KiB.
  Rounding size 500.00 MiB (125 extents) up to stripe boundary size 504.00 MiB(126 extents).
  Logical volume "LV" created.

# Now the expected behavior is to just keep running the same command over and over until it finally gets there? That seems like unprecedented lvm behavior.

[root@host-128 ~]# lvconvert --type raid10 VG/LV
  Using default stripesize 64.00 KiB.
  Replaced LV type raid10 (same as raid10_near) with possible type raid5_n.
  Repeat this command to convert to raid10 after an interim conversion has finished.
  Converting raid4 LV VG/LV to raid5_n.
Are you sure you want to convert raid4 LV VG/LV? [y/n]: y
  Logical volume VG/LV successfully converted.

[root@host-128 ~]# lvconvert --type raid10 VG/LV
  Using default stripesize 64.00 KiB.
  Replaced LV type raid10 (same as raid10_near) with possible type raid0_meta.
  Repeat this command to convert to raid10 after an interim conversion has finished.
Are you sure you want to convert raid5_n LV VG/LV to raid0_meta type? [y/n]: y
  Unable to convert VG/LV while it is not in-sync.

# Need to wait for sync and try again...

[root@host-128 ~]# lvconvert --type raid10 VG/LV
  Using default stripesize 64.00 KiB.
  Replaced LV type raid10 (same as raid10_near) with possible type raid0_meta.
  Repeat this command to convert to raid10 after an interim conversion has finished.
Are you sure you want to convert raid5_n LV VG/LV to raid0_meta type? [y/n]: y
  Logical volume VG/LV successfully converted.

[root@host-128 ~]# lvconvert --type raid10 VG/LV
  Using default stripesize 64.00 KiB.
Are you sure you want to convert raid0_meta LV VG/LV to raid10 type? [y/n]: y
  Logical volume VG/LV successfully converted.



Version-Release number of selected component (if applicable):
3.10.0-666.el7.x86_64

lvm2-2.02.171-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
lvm2-libs-2.02.171-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
lvm2-cluster-2.02.171-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
device-mapper-1.02.140-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
device-mapper-libs-1.02.140-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
device-mapper-event-1.02.140-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
device-mapper-event-libs-1.02.140-3.el7    BUILT: Wed May 31 08:36:29 CDT 2017
device-mapper-persistent-data-0.7.0-0.1.rc6.el7    BUILT: Mon Mar 27 10:15:46 CDT 2017
Comment 2 Heinz Mauelshagen 2017-06-02 12:33:42 UTC 
Upstream commit 3217e0cfeaed313332a0b69437ee87ca1f4b9e5e
Comment 3 Heinz Mauelshagen 2017-06-06 17:36:21 UTC 
Remove superfluous raid5_n interim LV type from raid4 -> raid10 conversion:

# lvs -aoname,size,segtype,attr,copypercent,stripes nvm
  LV           LSize  Type   Attr       Cpy%Sync #Str
  r            36.00m raid4  rwi-a-r--- 100.00      4
  [r_rimage_0] 12.00m linear iwi-aor---             1
  [r_rimage_1] 12.00m linear iwi-aor---             1
  [r_rimage_2] 12.00m linear iwi-aor---             1
  [r_rimage_3] 12.00m linear iwi-aor---             1
  [r_rmeta_0]   4.00m linear ewi-aor---             1
  [r_rmeta_1]   4.00m linear ewi-aor---             1
  [r_rmeta_2]   4.00m linear ewi-aor---             1
  [r_rmeta_3]   4.00m linear ewi-aor---             1

# lvconvert --type raid10 nvm/r
  Using default stripesize 64.00 KiB.
  Replaced LV type raid10 (same as raid10_near) with possible type raid0_meta.
  Repeat this command to convert to raid10 after an interim conversion has finished.
Are you sure you want to convert raid4 LV nvm/r to raid0_meta type? [y/n]: y
  Logical volume nvm/r successfully converted.

# lvconvert --type raid10 nvm/r
  Using default stripesize 64.00 KiB.
Are you sure you want to convert raid0_meta LV nvm/r to raid10 type? [y/n]: y

# lvs -aoname,size,segtype,attr,copypercent,stripes nvm
  LV           LSize  Type   Attr       Cpy%Sync #Str
  r            36.00m raid10 rwi-a-r--- 100.00      6
  [r_rimage_0] 12.00m linear iwi-aor---             1
  [r_rimage_1] 12.00m linear iwi-aor---             1
  [r_rimage_2] 12.00m linear iwi-aor---             1
  [r_rimage_3] 12.00m linear iwi-aor---             1
  [r_rimage_4] 12.00m linear iwi-aor---             1
  [r_rimage_5] 12.00m linear iwi-aor---             1
  [r_rmeta_0]   4.00m linear ewi-aor---             1
  [r_rmeta_1]   4.00m linear ewi-aor---             1
  [r_rmeta_2]   4.00m linear ewi-aor---             1
  [r_rmeta_3]   4.00m linear ewi-aor---             1
  [r_rmeta_4]   4.00m linear ewi-aor---             1
  [r_rmeta_5]   4.00m linear ewi-aor---             1