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Bug #16654

closed

the option 'rbd_cache_writethrough_until_flush=true' dosn't work

Added by Qi Yu almost 8 years ago. Updated over 7 years ago.

Status:
Resolved
Priority:
High
Assignee:
Jason Dillaman
Target version:
-
% Done:

0%

Source:
Community (user)
Tags:
Backport:
jewel
Regression:
No
Severity:
2 - major
Reviewed:
Affected Versions:
Ceph - v10.2.0
ceph-qa-suite:
rbd
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

Env: my ceph cluster with 252 SATA osds. the test VM kernerl version is ' 3.13.0-86-generic'

test cmd: sudo fio -name iops -rw=randwrite -bs=4k -direct=1 -thread -runtime=60 -iodepth 32 -filename /dev/vdb -ioengine=libaio

Test steps:

1. Test in the VM with 'rbd_cache_writethrough_until_flush=false' , the randwrite IOPS is 1000

2. Test in the VM with 'rbd_cache_writethrough_until_flush=true' , the randwrite IOPS is 3000

3. Test in the VM with 'rbd_cache_writethrough_until_flush=true' ,and excute 'sync' cmd to get a OS flush . but the randwrite iops is still IOPS.

So it looks like the rbd cache didn't switch from the writethrough to writeback mode .

rbd cache writethrough until flush

Description: Start out in write-through mode, and switch to write-back after the first flush request is received. Enabling this is a conservative but safe setting in case VMs running on rbd are too old to send flushes, like the virtio driver in Linux before 2.6.32.
Type: Boolean
Required: No
Default: true

Related issues 1 (0 open — 1 closed)

Copied to rbd - Backport #17080: jewel: the option 'rbd_cache_writethrough_until_flush=true' dosn't work ResolvedMykola GolubActions
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