Indeed, I would have thought that the unqualified setting would only ever be derived from _hdd / _ssd. I believe we have other sets of options that behave that way. > On Aug 18, 2023, at 13:54, Tony Liu <tonyliu0592@xxxxxxxxxxx> wrote: > > Hi Adam, > > This priority order is different from common sense, where specific setting has higher > priority than generic setting. With this order, compression_min_blob_size has higher > priority, then what's the point of having _hdd or _ssd settings, which will never get applied? > > > Thanks! > Tony > ________________________________________ > From: Adam Kupczyk <akupczyk@xxxxxxxxxx> > Sent: August 17, 2023 11:00 PM > To: Tony Liu > Cc: dev@xxxxxxx > Subject: Re: bluestore_compression_min_blob_size vs. bluestore_compression_min_blob_size_<type> > > Hi, > > First priority for compression blob is per-pool setting (taken if set) > # ceph osd pool get test compression_min_blob_size > Second, if set, bluestore_compression_min_blob_size config, > Third is selected from *_hdd *_ssd depending on the main block device in the OSD being HDD or SSD. > This can be forced by setting bluestore_debug_enforce_settings to either 'hdd' or 'ssd' if your hardware improperly reports > # cat /sys/block/sda/queue/rotational > 0 > > Blob is an organization unit in BlueStore > https://github.com/ceph/ceph/pull/51933 > > You can get compression for blocks smaller than 4K only if your main device has native block size smaller. > # cat /sys/block/nvme1n1/queue/physical_block_size > 512 > In such a case you can set bluestore_min_alloc_size (in effect only during mkfs) to some value smaller than 4K, but multiply of 512. > > This path is not often tested, and you need to own unexpected side effects. > > Best regards, > Adam Kupczyk > > > > > On Wed, 16 Aug 2023 at 19:46, Tony Liu <tonyliu0592@xxxxxxxxxxx<mailto:tonyliu0592@xxxxxxxxxxx>> wrote: > Hi, > > With Pacific and afterwards, which of the following two settings takes precedence? > bluestore_compression_min_blob_size (default 0) > bluestore_compression_min_blob_size_<type> (default 8192) > > I'd assume the more specific setting takes precedence? > What's this "blob"? Is it write block? > Then, there is no compression for 4K write block? > > I was not able to find it out from doc, hope someone could help to clarify. > > > Thanks! > Tony > _______________________________________________ > Dev mailing list -- dev@xxxxxxx<mailto:dev@xxxxxxx> > To unsubscribe send an email to dev-leave@xxxxxxx<mailto:dev-leave@xxxxxxx> > > _______________________________________________ > Dev mailing list -- dev@xxxxxxx > To unsubscribe send an email to dev-leave@xxxxxxx _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
