Quoting Wido den Hollander (wido@xxxxxxxx): > > > On 2/6/20 11:01 PM, Matt Larson wrote: > > Hi, we are planning out a Ceph storage cluster and were choosing > > between 64GB, 128GB, or even 256GB on metadata servers. We are > > considering having 2 metadata servers overall. > > > > Does going to high levels of RAM possibly yield any performance > > benefits? Is there a size beyond which there are just diminishing > > returns vs cost? > > > > The MDS will try to cache as much inodes as you allow it to. > > So the amount of users nor the total amount of bytes doesn't matter, > it's the amount of inodes, thus: files and directories. If clients are using unique datasets (files / directories) than the amount of clients do matter. If that is the case you might also ask yourself why you need a clustered filesystem, as it will definitely not speed things up compared to a local fs (metadata operations that is). > The more you have of those, the more memory it requires. To clarify: in (active) use. Just having a lot of data around does not necessarily require a lot of memory. > A lot of small files? A lot of memory! > > The expected use case would be for a cluster where there might be > > 10-20 concurrent users working on individual datasets of 5TB in size. > > I expect there would be lots of reads of the 5TB datasets matched with > > the creation of hundreds to thousands of smaller files during > > processing of the images. Hundreds to thousands of files is not a lot. Are these datasets to be stored permanently, or only temporarily? I guess it is convenient to just configure one fs for all clients to use, but it might not be the best fit / best performing solution in your case. Gr. Stefan -- | BIT BV https://www.bit.nl/ Kamer van Koophandel 09090351 | GPG: 0xD14839C6 +31 318 648 688 / info@xxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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