On Thu, Mar 1, 2018 at 5:37 PM, Subhachandra Chandra <schandra@xxxxxxxxxxxx> wrote: > Even with bluestore we saw memory usage plateau at 3-4GB with 8TB drives > filled to around 90%. One thing that does increase memory usage is the > number of clients simultaneously sending write requests to a particular > primary OSD if the write sizes are large. We have not seen a memory increase in Ubuntu 16.04, but I also observed repeatedly the following phenomenon: When doing a VMotion in ESXi of a large 3TB file (this generates a log of IO requests of small size) to a Ceph pool with compression set to force, after some time the Ceph cluster shows a large number of blocked requests and eventually timeouts become very large (to the point where ESXi aborts the IO due to timeouts). After abort, the blocked/slow requests messages disappear. There are no OSD errors. I have OSD logs if anyone is interested. This does not occur when compression is unset. -- Alex Gorbachev Storcium > > Subhachandra > > On Thu, Mar 1, 2018 at 6:18 AM, David Turner <drakonstein@xxxxxxxxx> wrote: >> >> With default memory settings, the general rule is 1GB ram/1TB OSD. If you >> have a 4TB OSD, you should plan to have at least 4GB ram. This was the >> recommendation for filestore OSDs, but it was a bit much memory for the >> OSDs. From what I've seen, this rule is a little more appropriate with >> bluestore now and should still be observed. >> >> Please note that memory usage in a HEALTH_OK cluster is not the same >> amount of memory that the daemons will use during recovery. I have seen >> deployments with 4x memory usage during recovery. >> >> On Thu, Mar 1, 2018 at 8:11 AM Stefan Kooman <stefan@xxxxxx> wrote: >>> >>> Quoting Caspar Smit (casparsmit@xxxxxxxxxxx): >>> > Stefan, >>> > >>> > How many OSD's and how much RAM are in each server? >>> >>> Currently 7 OSDs, 128 GB RAM. Max wil be 10 OSDs in these servers. 12 >>> cores (at least one core per OSD). >>> >>> > bluestore_cache_size=6G will not mean each OSD is using max 6GB RAM >>> > right? >>> >>> Apparently. Sure they will use more RAM than just cache to function >>> correctly. I figured 3 GB per OSD would be enough ... >>> >>> > Our bluestore hdd OSD's with bluestore_cache_size at 1G use ~4GB of >>> > total >>> > RAM. The cache is a part of the memory usage by bluestore OSD's. >>> >>> A factor 4 is quite high, isn't it? Where is all this RAM used for >>> besides cache? RocksDB? >>> >>> So how should I size the amount of RAM in a OSD server for 10 bluestore >>> SSDs in a >>> replicated setup? >>> >>> Thanks, >>> >>> Stefan >>> >>> -- >>> | BIT BV http://www.bit.nl/ Kamer van Koophandel 09090351 >>> | GPG: 0xD14839C6 +31 318 648 688 / info@xxxxxx >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@xxxxxxxxxxxxxx >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |