Hello, That is what I was thinking of doing as a plan B, just require more overhead on configuration of the VM, where cache tier does not require any per VM creation work. I guess as Christian said depends on the work load to which is the best option. ,Ashley -----Original Message----- From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Steffen Weißgerber Sent: 27 October 2016 10:30 To: ceph-users@xxxxxxxx; chibi@xxxxxxx Subject: Antw: Re: SSS Caching >>> Christian Balzer <chibi@xxxxxxx> schrieb am Donnerstag, 27. Oktober >>> 2016 um 04:07: Hi, > Hello, > > On Wed, 26 Oct 2016 15:40:00 +0000 Ashley Merrick wrote: > >> Hello All, >> >> Currently running a CEPH cluster connected to KVM via the KRBD and >> used only > for this purpose. >> >> Is working perfectly fine, however would like to look at increasing / > helping with random write performance and latency, specially from > multiple VM's hitting the spinning disks at same time. >> > Is it more a question of contention (HDDs being busy) or latency (lots > of small write I/Os)? > >> Currently have journals on SSD so helps with a very short burst, >> however > looking into putting some proper SSD "cache" in front. >> > You will want to read some of the recent and current "cache tier" > threads here, especially the "cache tiering deprecated in RHCS 2.0" > one, to which interestingly there hasn't been a single comment by RH > or the devs, official or otherwise. > Would the configuration of a seperat SSD only pool with corresponding crush rules an option to overcome the "cache tier is or will be deprecated" problematic? So that one could use separat SSD based rbd's in qemu vm's like one would install a mix of disks in a real PC tower (fast SSD for OS startup and datases and spinning disks for simple file storage). [...] Regards Steffen > > Christian > >> 3/ Anything I should be aware of when looking into caching? >> >> Thanks for your time!, >> Ashley >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > > > -- > Christian Balzer Network/Systems Engineer > chibi@xxxxxxx Global OnLine Japan/Rakuten Communications > http://www.gol.com/ > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com -- Klinik-Service Neubrandenburg GmbH Allendestr. 30, 17036 Neubrandenburg Amtsgericht Neubrandenburg, HRB 2457 Geschaeftsfuehrerin: Gudrun Kappich _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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