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IDProjectCategoryView StatusLast Update
0015729CentOS-7lvm2public2019-01-28 21:22
Reporterhunter86_bg 
PrioritynormalSeverityminorReproducibilityalways
Status newResolutionopen 
Product Version7.6.1810 
Target VersionFixed in Version 
Summary0015729: LVM cache cannot flush buffer,change cache type or lvremove (CachePolicy 'cleaner' also doesn't work)
DescriptionDescription of problem:
LVM cache in writeback mode cannot be changed to writethrough, nor it can be flushed to data lv.
Setting the CachePolicy 'cleaner' doesn't force lvm cache to be flushed.
lvremove fails also.

Version-Release number of selected component (if applicable):
libblockdev-lvm-2.18-3.el7.x86_64
lvm2-2.02.180-10.el7_6.2.x86_64
lvm2-libs-2.02.180-10.el7_6.2.x86_64
udisks2-lvm2-2.7.3-8.el7.x86_64

How reproducible:
Always.

Actual results:
cache_dirty_blocks are not flushed to data lv, thus an endless loop of 'Flushing xxxx blocks for cache VG/LV.'
Cleaner policy fails to flush the cache.
Lvremove cannot remove the LV.

Expected results:
All used blocks to be flushed during cache change/ uncache operations and during lv removal.
Steps To ReproduceSteps to Reproduce:
1. Follow official documentation for creation of lvm cache (use '--cachemode writeback')
2. Fill in some data - you will notice that cache_dirty_blocks won't get flashed
3. Set CachePolicy to 'cleaner'
4. Try to change the cache mode from 'writeback' to 'writethrough':
lvchange --cachemode writethrough VG/LV
5. Try to uncache:
lvconvert --uncache VG/LV
6. Try to remove LV:
lvremove VG/LV
Additional InformationAdditional info:
Other OS reports:
 https://www.reddit.com/r/archlinux/comments/9owc15/lvm_cache_not_flushing_after_unclean_shutdown/
https://marc.info/?l=linux-lvm&m=152948734523317&w=2
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hunter86_bg

hunter86_bg

2019-01-28 21:22

reporter   ~0033715

It seems the issue is well known.
The problem is that the chunk size is larger than the allowed migration threshold.

For workaround, check redhat bug 1668163.

Issue History

Date Modified Username Field Change
2019-01-22 04:54 hunter86_bg New Issue
2019-01-28 21:22 hunter86_bg Note Added: 0033715