[linux-lvm] Why is the performance of my lvmthin snapshot so poor

Zhiyong Ye yezhiyong at bytedance.com
Wed Jun 15 09:46:35 UTC 2022

在 6/15/22 5:34 PM, Gionatan Danti 写道:
> Il 2022-06-15 09:42 Zhiyong Ye ha scritto:
>> I regenerated the thin volume with the chunksize of 64K and the random
>> write performance data tested with fio 64k requests is as follows:
>> case                    iops
>> thin lv                 9381
>> snapshotted thin lv     8307
> As expected, increasing I/O size (to avoid r/m/w) greatly reduced the 
> issue (the ~11% hit is due to metadata allocation overhead).
> I don't see anything wrong, so I think you had to live with the 
> previously recorded 10x performance hit when overwriting 4K blocks on a 
> 64K chunk size thin volume...

I also think it meets expectations. But is there any other way to 
optimize snapshot performance at the code level? Does it help to reduce 
the chunksize size in the code, I see in the help documentation that the 
chunksize can only be 64k minimum.

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