Bug #42345
closed
OSD: When object compression ratio is high(but less than “bluestore_compression_required_ratio”), compression did not work
Added by Fengzhe Han over 4 years ago.
Updated over 4 years ago.
Description
Version: nautilus
I set value “.98” to “bluestore_compression_required_ratio”. Then put some objects into the cluster by rbd. The compress-type is zlib, and the object’s compression-rate is 93% more or less.But compression did not work.
I observed “ceph daemon osd.0 perf dump | grep bluestore”, and the relevant value didn’t change. Then I wrote some log to the source code and rebuild the Ceph projects.The log-print showed that the soft flow didn’t enter compression-path.
Fengzhe Han wrote:
Version: nautilus
I set value “.98” to “bluestore_compression_required_ratio”. Then put some objects into the cluster by rbd. The compress-type is zlib, and the object’s compression-rate is 93% more or less.But compression did not work.
I observed “ceph daemon osd.0 perf dump | grep bluestore”, and the relevant value didn’t change. Then I wrote some log to the source code and rebuild the Ceph projects.The log-print showed that the soft flow didn’t enter compression-path.
The parameters which I set :
bluestore_compression_algorithm = zlib
bluestore_compression_mode = force
bluestore_compression_required_ratio = .98
- Project changed from RADOS to bluestore
- Status changed from New to Need More Info
would you please set debug bluestore to 20, repeat the test and share the log? Thanks!
also please note that compression makes sense for writes that are at least 2x times as large as bluestore_min_alloc_size (16K/64K for SSD/HDD respectively). Smaller writes don't pass via compression path.
- Status changed from Need More Info to Closed
Sounds like there wasn't a bug here, just some confusion about config meaning.
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