On 10/7/2017 8:08 PM, David Turner wrote: > > Just to make sure you understand that the reads will happen on the > primary osd for the PG and not the nearest osd, meaning that reads > will go between the datacenters. Also that each write will not ack > until all 3 writes happen adding the latency to the writes and reads both. > >
Yes, I understand this. It is actually fine, the datacenters have been selected so that they are about 10-20km apart. This yields around a 0.1 - 0.2ms round trip time due to speed of light being too low. Nevertheless, latency due to network shouldn't be a problem and it's all 40G (dedicated) TRILL network for the moment. I just want to be able to select 1 SSD and 2 HDDs, all spread out. I can do that, but one of the HDDs end up in the same datacenter, probably because I'm using the "take" command 2 times (resets selecting buckets?). > On Sat, Oct 7, 2017, 1:48 PM Peter Linder <peter.lin...@fiberdirekt.se > <mailto:peter.lin...@fiberdirekt.se>> wrote: > > On 10/7/2017 7:36 PM, Дробышевский, Владимир wrote: >> Hello! >> >> 2017-10-07 19:12 GMT+05:00 Peter Linder >> <peter.lin...@fiberdirekt.se <mailto:peter.lin...@fiberdirekt.se>>: >> >> The idea is to select an nvme osd, and >> then select the rest from hdd osds in different datacenters >> (see crush >> map below for hierarchy). >> >> It's a little bit aside of the question, but why do you want to >> mix SSDs and HDDs in the same pool? Do you have read-intensive >> workload and going to use primary-affinity to get all reads from >> nvme? >> >> > Yes, this is pretty much the idea, getting the performance from > NVMe reads, while still maintaining triple redundancy and a > reasonable cost. > > >> -- >> Regards, >> Vladimir > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com <mailto:ceph-users@lists.ceph.com> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
_______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
