Filestore had no such recommendation for size of journal per TB. The default was a flat 10GB partition. For bluestore, the recommendation has been 10GB per TB. However, with your setup, I would probably bump that up a bit more just to give you more room for your WAL/DB partition. While bluestore _can_ spill over to the spinning disk, it will slow your speeds and create performance issues that may be hard to track down.
On Wed, Mar 21, 2018 at 6:38 AM Ján Senko <jan.se...@gmail.com> wrote: > 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 <+420%20777%20843%20818> > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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