Maneul, thank you for your input. This is actually huge, and the problem is exactly that. On a side note I will add, that I observed lower memory utilisation on OSD nodes since the update, and a big throughput on block.db devices(up to 100+MB/s) that was not there before, so logically that meant that some operations that were performed in memory before, now were executed directly on block device. Was digging through possible causes, but your time-saving message arrived earlier. Thank you! чт, 6 авг. 2020 г. в 14:56, Manuel Lausch <manuel.lausch@1und1.de>:
Hi,
I found the reasen of this behavior change. With 14.2.10 the default value of "bluefs_buffered_io" was changed from true to false. https://tracker.ceph.com/issues/44818
configureing this to true my problems seems to be solved.
Regards Manuel
On Wed, 5 Aug 2020 13:30:45 +0200 Manuel Lausch <manuel.lausch@1und1.de> wrote:
Hello Vladimir,
I just tested this with a single node testcluster with 60 HDDs (3 of them with bluestore without separate wal and db).
With the 14.2.10, I see on the bluestore OSDs a lot of read IOPs while snaptrimming. With 14.2.9 this was not an issue.
I wonder if this would explain the huge amount of slowops on my big testcluster (44 Nodes 1056 OSDs) while snaptrimming. I cannot test a downgrade there, because there are no packages of older releases for CentOS 8 available.
Regards Manuel
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