2018-03-21 8:56 GMT+01:00 Caspar Smit <caspars...@supernas.eu>: > 2018-03-21 7:20 GMT+01:00 ST Wong (ITSC) <s...@itsc.cuhk.edu.hk>: > >> Hi all, >> >> >> >> We got some decommissioned servers from other projects for setting up >> OSDs. They’ve 10 2TB SAS disks with 4 2TB SSD. >> >> We try to test with bluestores and hope to play wal and db devices on >> SSD. Need advice on some newbie questions: >> >> >> >> 1. As there are more SAS than SSD, is it possible/recommended to put wal >> and db of multiple OSDs in partitions on same SSD (instead of using whole >> SSD device) ? >> >> > Yes, that's common practice. Although the general advice is no more then 5 > OSD's per wal/db SSD. >
I understand this was general advice in the FileStore era, because *all* writes had to go through journal first. However IIRC in BlueStore only some writes need to go to db? Is this number therefore different now? > > >> 2. if ok to do 1., how to size the SSD partition for wal/db ? >> > > ~ 10GB per TB. In your case 20GB partitions for 2TB drives. > > Again, this was common for FileStore Journals. As we know BlueStore can live without separate db, and will store excess db on the drive itself. What is the current recommendation? > 3. do we need to tune parameters like bluestore_cache_size_ssd when SSD >> is used in OSD? >> >> >> > > Only if your low on RAM. > > Caspar > > Thanks a lot. >> >> Best Regards, >> >> /ST Wong >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > -- Jan Senko, Skype janos- Phone in Switzerland: +41 774 144 602 Phone in Czech Republic: +420 777 843 818
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