Ok, now if I run a lab and the data is somewhat important but I can bare losing the data, couldn't I shrink the pool replica count and that increases the amount of storage I can use without using erasure coding?
So for 145TB with a replica of 3 = ~41 TB total in the cluster But if that same clusters replica was decreased to 2 I could possibly get 145TB / 2 - overhead for cluster and get ~65TB in the cluster at one time..correct? Thanks in advance! On Mar 12, 2015 11:53 AM, "Kamil Kuramshin" <[email protected]> wrote: > For example, here is my confuguration: > > superuser@admin:~$ ceph df > GLOBAL: > SIZE AVAIL RAW USED %RAW USED > 242T 209T 20783G 8.38 > POOLS: > NAME ID USED %USED MAX AVAIL OBJECTS > ec_backup-storage 4 9629G 3.88 137T 2465171 > cache 5 136G 0.06 38393M 35036 > block-devices 6 1953G 0.79 70202G 500060 > > > *ec_backup-storage* - is Erasure Encoded pool, k=2, m=1 (default) > *cache* - is replicated pool consisting dedicated 12xSSDx60Gb disks, > replica size=3, used as cache tier for EC pool > *block-devices* - is replicated pool, replica size=3, using same OSD's > that in Erasure Encoded pool > > On* '**MAX AVAIL**'* column you can see that EC pool currently has *137Tb* > of free space, but in same time if we will write to replicated pool there > is only *70Tb, *but *both* pools are on the *same* *OSD's. *So using EC > pool saves 2 times more effective space in my case! > > 12.03.2015 17:50, Thomas Foster пишет: > > Thank you! That helps alot. > On Mar 12, 2015 10:40 AM, "Steve Anthony" <[email protected]> wrote: > >> Actually, it's more like 41TB. It's a bad idea to run at near full >> capacity (by default past 85%) because you need some space where Ceph can >> replicate data as part of its healing process in the event of disk or node >> failure. You'll get a health warning when you exceed this ratio. >> >> You can use erasure coding to increase the amount of data you can store >> beyond 41TB, but you'll still need some replicated disk as a caching layer >> in front of the erasure coded pool if you're using RBD. See: >> http://lists.ceph.com/pipermail/ceph-users-ceph.com/2013-December/036430.html >> >> As to how much space you can save with erasure coding, that will depend >> on if you're using RBD and need a cache layer and the values you set for k >> and m (number of data chunks and coding chunks). There's been some >> discussion on the list with regards to choosing those values. >> >> -Steve >> >> On 03/12/2015 10:07 AM, Thomas Foster wrote: >> >> I am looking into how I can maximize my space with replication, and I am >> trying to understand how I can do that. >> >> I have 145TB of space and a replication of 3 for the pool and was >> thinking that the max data I can have in the cluster is ~47TB in my cluster >> at one time..is that correct? Or is there a way to get more data into the >> cluster with less space using erasure coding? >> >> Any help would be greatly appreciated. >> >> >> >> >> _______________________________________________ >> ceph-users mailing >> [email protected]http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> >> -- >> Steve Anthony >> LTS HPC Support Specialist >> Lehigh [email protected] >> >> >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> > > _______________________________________________ > ceph-users mailing > [email protected]http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >
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