Hello Christian, > Hello, > > On Wed, 18 May 2016 13:57:59 +0200 Dietmar Rieder wrote: > >> Dear Ceph users, >> >> I've a question regarding the memory recommendations for an OSD node. >> >> The official Ceph hardware recommendations say that an OSD node should >> have 1GB Ram / TB OSD [1] >> >> The "Reference Architecture" whitpaper from Red Hat & Supermicro says >> that "typically" 2GB of memory per OSD on a OSD node is used. [2] >> > This question has been asked and answered here countless times. > > Maybe something a bit more detailed ought to be placed in the first > location, or simply a reference to the 2nd one. > But then again, that would detract from the RH added value. thanks for replying, nonetheless. I checked the list before but I failed to find a definitive answer, may be I was not looking hard enough. Anyway, thanks! > >> According to the recommendation in [1] an OSD node with 24x 8TB OSD >> disks is "underpowered " when it is equipped with 128GB of RAM. >> However, following the "recommendation" in [2] 128GB should be plenty >> enough. >> > It's fine per se, the OSD processes will not consume all of that even in > extreme situations. Ok, if I understood this correctly, then 128GB should be enough also during rebalancing or backfilling. > > Very large OSDs and high density storage nodes have other issues and > challenges, tuning and memory wise. > There are several threads about these recently, including today. Thanks, I'll study these... >> I'm wondering which of the two is good enough for a Ceph cluster with 10 >> nodes using EC (6+3) >> > I would spend more time pondering about the CPU power of these machines > (EC need more) and what cache tier to get. We are planing to equip the OSD nodes with 2x2650v4 CPUs (24 cores @ 2.2GHz), that is 1 core/OSD. For the cache tier each OSD node gets two 800Gb NVMe's. We hope this setup will give reasonable performance with EC. > That is, if performance is a requirement in your use case. Always, who wouldn't care about performance? :-) Dietmar -- _________________________________________ D i e t m a r R i e d e r, Mag.Dr. Innsbruck Medical University Biocenter - Division for Bioinformatics Innrain 80, 6020 Innsbruck Phone: +43 512 9003 71402 Fax: +43 512 9003 73100 Email: dietmar.rieder@xxxxxxxxxxx Web: http://www.icbi.at
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