Rather than a cache tier, I would put an NVMe device in each OSD box for Bluestore's DB and WAL. This will significantly improve small IOs. 14*16 HDDs / 11 chunks = 20 HDD's worth of write IOPs. If you expect these files to be written sequentially, this is probably ok. Mons and mgr on OSD nodes should be ok as far as I know (we are doing it). However, if you use CephFS, you will want the fastest CPUs you can get for the MDS, as it only scales to 2-3 cores in our tests. I would avoid the complexity of CephFS if you do not need POSIX semantics. On Tue, Dec 3, 2019 at 3:07 PM Fabien Sirjean <fsirjean@xxxxxxxxxxxx> wrote: > > Hi Ceph users ! > > After years of using Ceph, we plan to build soon a new cluster bigger than what > we've done in the past. As the project is still in reflection, I'd like to > have your thoughts on our planned design : any feedback is welcome :) > > > ## Requirements > > * ~1 PB usable space for file storage, extensible in the future > * The files are mostly "hot" data, no cold storage > * Purpose : storage for big files being essentially used on windows workstations (10G access) > * Performance is better :) > > > ## Global design > > * 8+3 Erasure Coded pool > * ZFS on RBD, exposed via samba shares (cluster with failover) > > > ## Hardware > > * 1 rack (multi-site would be better, of course...) > > * OSD nodes : 14 x supermicro servers > * 24 usable bays in 2U rackspace > * 16 x 10 TB nearline SAS HDD (8 bays for future needs) > * 2 x Xeon Silver 4212 (12C/24T) > * 128 GB RAM > * 4 x 40G QSFP+ > > * Networking : 2 x Cisco N3K 3132Q or 3164Q > * 2 x 40G per server for ceph network (LACP/VPC for HA) > * 2 x 40G per server for public network (LACP/VPC for HA) > * QSFP+ DAC cables > > > ## Sizing > > If we've done the maths well, we expect to have : > > * 2.24 PB of raw storage, extensible to 3.36 PB by adding HDD > * 1.63 PB expected usable space with 8+3 EC, extensible to 2.44 PB > * ~1 PB of usable space if we want to keep the OSD use under 66% to allow > loosing nodes without problem, extensible to 1.6 PB (same condition) > > > ## Reflections > > * We're used to run mons and mgrs daemons on a few of our OSD nodes, without > any issue so far : is this a bad idea for a big cluster ? > > * We thought using cache tiering on an SSD pool, but a large part of the PB is > used on a daily basis, so we expect the cache to be not so effective and > really expensive ? > > * Could a 2x10G network be enough ? > > * ZFS on Ceph ? Any thoughts ? > > * What about CephFS ? We'd like to use RBD diff for backups but it looks > impossible to use snapshot diff with Cephfs ? > > > Thanks for reading, and sharing your experiences ! > > F. > > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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