Bug 1021955

Summary: Copy/Sync percentage drops when maxrecoveryrate is changed on a RAID LV
Product: Red Hat Enterprise Linux 6 Reporter: Nenad Peric <nperic>
Component: lvm2Assignee: Jonathan Earl Brassow <jbrassow>
Status: CLOSED WORKSFORME QA Contact: Cluster QE <mspqa-list>
Severity: low Docs Contact:
Priority: low    
Version: 6.5CC: agk, dwysocha, heinzm, jbrassow, msnitzer, nperic, prajnoha, prockai, thornber, zkabelac
Target Milestone: rc   
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Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2014-04-09 10:53:29 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Blocks: 1075263    
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Description Flags
Test I'm using to verify reported percentages do not drop. none

Description Nenad Peric 2013-10-22 11:54:47 UTC 
Description of problem:


Version-Release number of selected component (if applicable):


How reproducible:

95% of the time 

Steps to Reproduce:

Create many raids with maxrecoveryrate of, say, 512.
Then wait a bit while the sync goes under way. 
Change the recovery rates of some LVs, and the sync percentage will often drop below the value before the change.


Actual results:
[root@virt-008 ~]# lvchange raid/lvol3 --maxrecoveryrate 2048
  Logical volume "lvol3" changed.

[root@virt-008 ~]# lvs
  LV      VG         Attr       LSize   Pool Origin Data%  Move Log Cpy%Sync Convert
  lvol0   raid       rwi-a-r---   1.00g                                 8.59        
  lvol1   raid       rwi-a-r---   1.00g                                 8.59        
  lvol2   raid       rwi-a-r---   1.00g                                 8.59        
  lvol3   raid       rwi-a-r---   1.00g                                 8.98        
  lvol4   raid       rwi-a-r---   1.00g                                 8.59        

[root@virt-008 ~]# lvchange raid/lvol1 --maxrecoveryrate 2048
  Logical volume "lvol1" changed.
[root@virt-008 ~]# lvs
  LV      VG         Attr       LSize   Pool Origin Data%  Move Log Cpy%Sync Convert
  lvol0   raid       rwi-a-r---   1.00g                                 9.38        
  lvol1   raid       rwi-a-r---   1.00g                                 6.25        
  lvol2   raid       rwi-a-r---   1.00g                                 9.38        
  lvol3   raid       rwi-a-r---   1.00g                                10.94        
  lvol4   raid       rwi-a-r---   1.00g                                 8.98        

The sync percentage dropped for lvol1 from 8.59 to 6.25.
On lower percentages (up to 5) it drops to 0. 


Expected results:

That the percentage stays the same (or higher) after the lvchange since the recovery rate setting should only speed up or slow down the process, not reverse it (if I understood it corrrectly). 


Tested with:

lvm2-2.02.100-6.el6.x86_64

This behavior was first seen in verification of Bug 969171 (https://bugzilla.redhat.com/show_bug.cgi?id=969171#c9)
Comment 2 RHEL Program Management 2013-10-27 08:05:32 UTC 
This request was not resolved in time for the current release.
Red Hat invites you to ask your support representative to
propose this request, if still desired, for consideration in
the next release of Red Hat Enterprise Linux.
Comment 4 Jonathan Earl Brassow 2014-04-01 17:52:01 UTC 
Does the recovery rate have to be changed in a particular direction?  My script is currently increasing the rate, but never decreasing.

I'll attach the script I'm using.
Comment 5 Jonathan Earl Brassow 2014-04-01 17:53:58 UTC 
Created attachment 881466 [details]
Test I'm using to verify reported percentages do not drop.

My test currently only increases recovery rate.  It also assumes a VG name of 'vg'.
Comment 6 Jonathan Earl Brassow 2014-04-02 04:52:17 UTC 
(In reply to Jonathan Earl Brassow from comment #5)
> Created attachment 881466 [details]
> Test I'm using to verify reported percentages do not drop.
> 
> My test currently only increases recovery rate.  It also assumes a VG name
> of 'vg'.

If you want this test to work well, you will probably have to:
s/
rate=$((${a[1]} + 100))
/
rate=$((10#${a[1]} + 100))
/
Otherwise, some of the percent numbers will be improperly converted to octal.
Comment 7 Nenad Peric 2014-04-03 13:29:42 UTC 
I was not increasing or decreasing.
I was actually sending the same number to the change command, as stated in the opening comment. 
However, I'll test it again with the newest build with increasing and decreasing and see what hapens.
Comment 8 Jonathan Earl Brassow 2014-04-08 20:59:39 UTC 
I've tested again and by creating with a rate of 512 and changing to a rate of 2048, like in the opening comment.  I still cannot reproduce.
Comment 9 Nenad Peric 2014-04-09 08:51:27 UTC 
Ok, I will re-test it today again with the newest LVM build and post back the results. Maybe it is no longer happening.
Comment 10 Nenad Peric 2014-04-09 09:51:10 UTC 
I cannot seem to reproduce this anymore. 

So whatever has changed in the meantime, this percentage remains the same or grows faster, as would be expected with the increase of the recovery rate. 

I suppose that this bug can now be closed as such, and if I run into it again in the future, I will open a new one (or re-open this one..)