I think this depends on the type of backing disk. We use the following CPUs:
Intel(R) Xeon(R) CPU E5-2660 v4 @ 2.00GHz Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz Intel(R) Xeon(R) Silver 4216 CPU @ 2.10GHz My experience is, that a HDD OSD hardly gets to 100% of 1 hyper thread load even under heavy recovery/rebalance operations on 8+2 and 6+2 EC pools with compression set to aggressive. The CPU is mostly doing wait-IO, that is, the disk is the real bottle neck, not the processor power. With SSDs I have seen 2HT at 100% and 2 more at 50% each. I guess NVMe might be more demanding. A server with 12 HDD and 1 SSD should be fine with a modern CPU with 8 cores. 16 threads sounds like an 8 core CPU. The 2nd generation Intel® Xeon® Silver 4209T with 8 cores should easily handle that (single socket system). We have the 16-core Intel silver in a dual socket system currently connected to 5HDD and 7SSD and I did a rebalance operation yesterday. The CPU user load did not exceed 2%, it can handle OSD processes easily. The server is dimensioned to run up to 12HDD and 14SSD OSDs (Dell R740xd2). As far as I can tell, the CPU configuration is overpowered for that. Just for info, we use ganglia to record node utilisation. I use 1-year records and pick peak loads I observed for dimensioning the CPUs. These records include some very heavy recovery periods. Best regards, ================= Frank Schilder AIT Risø Campus Bygning 109, rum S14 ________________________________________ From: Tony Liu <tonyliu0...@hotmail.com> Sent: 13 November 2020 04:57:53 To: Nathan Fish Cc: ceph-users@ceph.io Subject: [ceph-users] Re: which of cpu frequency and number of threads servers osd better? Thanks Nathan! Tony > -----Original Message----- > From: Nathan Fish <lordci...@gmail.com> > Sent: Thursday, November 12, 2020 7:43 PM > To: Tony Liu <tonyliu0...@hotmail.com> > Cc: ceph-users@ceph.io > Subject: Re: [ceph-users] which of cpu frequency and number of threads > servers osd better? > > From what I've seen, OSD daemons tend to bottleneck on the first 2 > threads, while getting some use out of another 2. So 32 threads at 3.0 > would be a lot better. Note that you may get better performance > splitting off some of that SSD for block.db partitions or at least > block.wal for the HDDs. > > On Thu, Nov 12, 2020 at 9:57 PM Tony Liu <tonyliu0...@hotmail.com> wrote: > > > > Hi, > > > > For example, 16 threads with 3.2GHz and 32 threads with 3.0GHz, which > > makes 11 OSDs (10x12TB HDD and 1x960GB SSD) with better performance? > > > > > > Thanks! > > Tony > > _______________________________________________ > > ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an > > email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
