Hi guys, Could someone from the ceph team please comment on running osd cache pool on the hypervisors? Is this a good idea, or will it create a lot of performance issues?
Anyone in the ceph community that has done this? Any results to share? Many thanks Andrei ----- Original Message ----- > From: "Robert van Leeuwen" <robert.vanleeu...@spilgames.com> > To: "Andrei Mikhailovsky" <and...@arhont.com> > Cc: ceph-users@lists.ceph.com > Sent: Thursday, 14 August, 2014 9:31:24 AM > Subject: RE: cache pools on hypervisor servers > > Personally I am not worried too much about the hypervisor - hypervisor > > traffic as I am using a dedicated infiniband network for storage. > > It is not used for the guest to guest or the internet traffic or anything > > else. I would like to decrease or at least smooth out the traffic peaks > > between the hypervisors and the SAS/SATA osd storage servers. > > I guess the ssd cache pool would enable me to do that as the eviction rate > > should be more structured compared to the random io writes that guest vms > > generate. > Sounds reasonable > >>I'm very interested in the effect of caching pools in combination with > >>running VMs on them so I'd be happy to hear what you find ;) > > I will give it a try and share back the results when we get the ssd kit. > Excellent, looking forward to it. > >> As a side note: Running OSDs on hypervisors would not be my preferred > >> choice since hypervisor load might impact Ceph performance. > > Do you think it is not a good idea even if you have a lot of cores on the > > hypervisors? > > Like 24 or 32 per host server? > > According to my monitoring, our osd servers are not that stressed and > > generally have over 50% of free cpu power. > The number of cores do not really matter if they are all busy ;) > I honestly do not know how Ceph behaves when it is CPU starved but I guess it > might not be pretty. > Since your whole environment will be crumbling down if your storage becomes > unavailable it is not a risk I would take lightly. > Cheers, > Robert van Leeuwen
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