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Bug 1778977

Summary: after pvmove-ing LV from PV1 that uses read-ahead X to PV2 that uses read-ahead Y - LV on new destination should deduce RA from PV2.
Product: Red Hat Enterprise Linux 7 Reporter: Corey Marthaler <cmarthal>
Component: lvm2Assignee: Zdenek Kabelac <zkabelac>
lvm2 sub component: Other QA Contact: cluster-qe <cluster-qe>
Status: CLOSED WONTFIX Docs Contact:
Severity: medium    
Priority: unspecified CC: agk, heinzm, jbrassow, msnitzer, prajnoha, zkabelac
Version: 7.8   
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1899571 (view as bug list) Environment:
Last Closed: 2020-11-19 15:21:24 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: 1899571    

Description Corey Marthaler 2019-12-03 00:44:41 UTC 
Description of problem:
This is the issue requested to be tested in: https://bugzilla.redhat.com/show_bug.cgi?id=1722860#c9

And shown not to work in:
https://bugzilla.redhat.com/show_bug.cgi?id=1722860#c11


lvm2-2.02.186-2.el7.x86_64

# cat /sys/block/sd{a..b}/queue/read_ahead_kb
256
128

not using any 'preset' RA value for lv (reference to second sentence in Comment 9):
# lvcreate -n mylv -L100M vg /dev/sda
  Logical volume "mylv" created.

# ls -la /dev/mapper/vg-mylv
lrwxrwxrwx. 1 root root 7 Oct 10 11:25 /dev/mapper/vg-mylv -> ../dm-2

# lvs -o lv_name,devices vg
  LV   Devices
  mylv /dev/sdb(0)

# cat /sys/block/dm-2/queue/read_ahead_kb
128

# pvmove /dev/sdb /dev/sda
  /dev/sdb: Moved: 20.00%
  /dev/sdb: Moved: 100.00%


lv should have deduced RA of 256kb from /dev/sda but remained unchanged:
# cat /sys/block/dm-2/queue/read_ahead_kb
128
Comment 2 Zdenek Kabelac 2020-11-19 15:21:24 UTC 
Cloned for futher investigation as bug 1899571 for RH8 - as RH7 is done.