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Am 30.08.2013 20:33, schrieb Wido den Hollander:
On 08/30/2013 08:19 PM, Geraint Jones wrote: I think that would be ok if ceph wouldn't consume that much memory. On a relatively small cluster with currently 16 OSDs and 8192 PGs (2 pools with 4096 pgs each) each osd consumes around 2-4 GB ram. So with 24 disks the machine would need at least 96 GB ram, just for the osds. With some memory left for the page cache etc. 128 GB would be the minimum. Anyway, I think this is a bug and already filed a report for it here: http://tracker.ceph.com/issues/5700 To be honest I'm a little disappointed by the last answer there, because 8192 isn't a lot of pgs? The docs say 50-100 pgs per osds per pool. So 2 pools with 4096 pgs each just allows for 40 - 80 osds - which isn't really that much? There's also a big discrepancy with the docs, as they state an osd would consume 200 - 500 mb ( http://ceph.com/docs/next/install/hardware-recommendations/). I know David is still waiting for a detailed debug log from me, which I'll provide within a short while. But if ceph's memory requirements are really that high, fixing the docs to allow for proper resource planing is really a must. I'm curious what memory usage other users are experiencing? Cheers, Corin |
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