> -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Christian Balzer > Sent: 21 August 2016 09:32 > To: ceph-users <ceph-users@xxxxxxxxxxxxxx> > Subject: Re: Ceph + VMware + Single Thread Performance > > > Hello, > > On Sun, 21 Aug 2016 09:16:33 +0100 Brian :: wrote: > > > Hi Nick > > > > Interested in this comment - "-Dual sockets are probably bad and will > > impact performance." > > > > Have you got real world experience of this being the case? > > > Well, Nick wrote "probably". > > Dual sockets and thus NUMA, the need for CPUs to talk to each other and share information certainly can impact things that are very > time critical. > How much though is a question of design, both HW and SW. There was a guy from Redhat (sorry his name escapes me now) a few months ago on the performance weekly meeting. He was analysing the CPU cache miss effects with Ceph and it looked like a NUMA setup was having quite a severe impact on some things. To be honest a lot of it went over my head, but I came away from it with a general feeling that if you can get the required performance from 1 socket, then that is probably a better bet. This includes only populating a single socket in a dual socket system. There was also a Ceph tech talk at the start of the year (High perf databases on Ceph) where the guy presenting was also recommending only populating 1 socket for latency reasons. Both of those, coupled with the fact that Xeon E3's are the cheapest way to get high clock speeds, sort of made my decision. > > We're looking here at a case where he's trying to reduce latency by all means and where the actual CPU needs for the HDDs are > negligible. > The idea being that a "Ceph IOPS" stays on one core which is hopefully also not being shared at that time. > > If you're looking at full SSD nodes OTOH a singe CPU may very well not be able to saturate a sensible amount of SSDs per node, so a > slight penalty but better utilization and overall IOPS with 2 CPUs may be the forward. Definitely, as always work out what your requirements are and design around them. > > Christian > > > Thanks - B > > > > On Sun, Aug 21, 2016 at 8:31 AM, Nick Fisk <nick@xxxxxxxxxx> wrote: > > >> -----Original Message----- > > >> From: Alex Gorbachev [mailto:ag@xxxxxxxxxxxxxxxxxxx] > > >> Sent: 21 August 2016 04:15 > > >> To: Nick Fisk <nick@xxxxxxxxxx> > > >> Cc: wr@xxxxxxxx; Horace Ng <horace@xxxxxxxxx>; ceph-users > > >> <ceph-users@xxxxxxxxxxxxxx> > > >> Subject: Re: Ceph + VMware + Single Thread Performance > > >> > > >> Hi Nick, > > >> > > >> On Thu, Jul 21, 2016 at 8:33 AM, Nick Fisk <nick@xxxxxxxxxx> wrote: > > >> >> -----Original Message----- > > >> >> From: wr@xxxxxxxx [mailto:wr@xxxxxxxx] > > >> >> Sent: 21 July 2016 13:23 > > >> >> To: nick@xxxxxxxxxx; 'Horace Ng' <horace@xxxxxxxxx> > > >> >> Cc: ceph-users@xxxxxxxxxxxxxx > > >> >> Subject: Re: Ceph + VMware + Single Thread > > >> >> Performance > > >> >> > > >> >> Okay and what is your plan now to speed up ? > > >> > > > >> > Now I have come up with a lower latency hardware design, there is > > >> > not much further improvement until persistent RBD caching is > > >> implemented, as you will be moving the SSD/NVME closer to the > > >> client. But I'm happy with what I can achieve at the moment. You could also experiment with bcache on the RBD. > > >> > > >> Reviving this thread, would you be willing to share the details of > > >> the low latency hardware design? Are you optimizing for NFS or iSCSI? > > > > > > Both really, just trying to get the write latency as low as possible, as you know, vmware does everything with lots of unbuffered > small io's. Eg when you migrate a VM or as thin vmdk's grow. > > > > > > Even storage vmotions which might kick off 32 threads, as they all roughly fall on the same PG, there still appears to be a > bottleneck with contention on the PG itself. > > > > > > These were the sort of things I was trying to optimise for, to make the time spent in Ceph as minimal as possible for each IO. > > > > > > So onto the hardware. Through reading various threads and experiments on my own I came to the following conclusions. > > > > > > -You need highest possible frequency on the CPU cores, which normally also means less of them. > > > -Dual sockets are probably bad and will impact performance. > > > -Use NVME's for journals to minimise latency > > > > > > The end result was OSD nodes based off of a 3.5Ghz Xeon E3v5 with an Intel P3700 for a journal. I used the SuperMicro X11SSH- > CTF board which has 10G-T onboard as well as 8SATA and 8SAS, so no expansion cards required. Actually this design as well as being > very performant for Ceph, also works out very cheap as you are using low end server parts. The whole lot + 12x7.2k disks all goes into > a 1U case. > > > > > > During testing I noticed that by default c-states and p-states slaughter performance. After forcing max cstate to 1 and forcing the > CPU frequency up to max, I was seeing 600us latency for a 4kb write to a 3xreplica pool, or around 1600IOPs, this is at QD=1. > > > > > > Few other observations: > > > 1. Power usage is around 150-200W for this config with 12x7.2k disks > > > 2. CPU usage maxing out disks, is only around 10-15%, so plenty of headroom for more disks. > > > 3. NOTE FOR ABOVE: Don't include iowait when looking at CPU usage 4. > > > No idea about CPU load for pure SSD nodes, but based on the current > > > disks, you could maybe expect ~10000iops per node, before maxing out CPU's 5. Single NVME seems to be able to journal 12 disks > with no problem during normal operation, no doubt a specific benchmark could max it out though. > > > 6. There are slightly faster Xeon E3's, but price/performance = > > > diminishing returns > > > > > > Hope that answers all your questions. > > > Nick > > > > > >> > > >> Thank you, > > >> Alex > > >> > > >> > > > >> >> > > >> >> Would it help to put in multiple P3700 per OSD Node to improve performance for a single Thread (example Storage VMotion) > ? > > >> > > > >> > Most likely not, it's all the other parts of the puzzle which are > > >> > causing the latency. ESXi was designed for storage arrays that > > >> > service > > >> IO's in 100us-1ms range, Ceph is probably about 10x slower than > > >> this, hence the problem. Disable the BBWC on a RAID controller or SAN and you will the same behaviour. > > >> > > > >> >> > > >> >> Regards > > >> >> > > >> >> > > >> >> Am 21.07.16 um 14:17 schrieb Nick Fisk: > > >> >> >> -----Original Message----- > > >> >> >> From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] > > >> >> >> On Behalf Of wr@xxxxxxxx > > >> >> >> Sent: 21 July 2016 13:04 > > >> >> >> To: nick@xxxxxxxxxx; 'Horace Ng' <horace@xxxxxxxxx> > > >> >> >> Cc: ceph-users@xxxxxxxxxxxxxx > > >> >> >> Subject: Re: Ceph + VMware + Single Thread > > >> >> >> Performance > > >> >> >> > > >> >> >> Hi, > > >> >> >> > > >> >> >> hmm i think 200 MByte/s is really bad. Is your Cluster in production right now? > > >> >> > It's just been built, not running yet. > > >> >> > > > >> >> >> So if you start a storage migration you get only 200 MByte/s right? > > >> >> > I wish. My current cluster (not this new one) would storage > > >> >> > migrate at ~10-15MB/s. Serial latency is the problem, without > > >> >> > being able to buffer, ESXi waits on an ack for each IO before sending the next. > > >> >> > Also it submits the migrations in 64kb chunks, unless you get > > >> >> > VAAI > > >> >> working. I think esxi will try and do them in parallel, which will help as well. > > >> >> > > > >> >> >> I think it would be awesome if you get 1000 MByte/s > > >> >> >> > > >> >> >> Where is the Bottleneck? > > >> >> > Latency serialisation, without a buffer, you can't drive the > > >> >> > devices to 100%. With buffered IO (or high queue depths) I can max out the journals. > > >> >> > > > >> >> >> A FIO Test from Sebastien Han give us 400 MByte/s raw performance from the P3700. > > >> >> >> > > >> >> >> https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test > > >> >> >> -if-y our -ssd-is-suitable-as-a-journal-device/ > > >> >> >> > > >> >> >> How could it be that the rbd client performance is 50% slower? > > >> >> >> > > >> >> >> Regards > > >> >> >> > > >> >> >> > > >> >> >> Am 21.07.16 um 12:15 schrieb Nick Fisk: > > >> >> >>> I've had a lot of pain with this, smaller block sizes are even worse. > > >> >> >>> You want to try and minimize latency at every point as there > > >> >> >>> is no buffering happening in the iSCSI stack. This means:- > > >> >> >>> > > >> >> >>> 1. Fast journals (NVME or NVRAM) 2. 10GB or better > > >> >> >>> networking 3. Fast CPU's (Ghz) 4. Fix CPU c-state's to C1 5. > > >> >> >>> Fix CPU's Freq to max > > >> >> >>> > > >> >> >>> Also I can't be sure, but I think there is a metadata update > > >> >> >>> happening with VMFS, particularly if you are using thin > > >> >> >>> VMDK's, this can also be a major bottleneck. For my use > > >> >> >>> case, I've switched over to NFS as it has given much more > > >> >> >>> performance at scale and > > >> >> less headache. > > >> >> >>> > > >> >> >>> For the RADOS Run, here you go (400GB P3700): > > >> >> >>> > > >> >> >>> Total time run: 60.026491 > > >> >> >>> Total writes made: 3104 > > >> >> >>> Write size: 4194304 > > >> >> >>> Object size: 4194304 > > >> >> >>> Bandwidth (MB/sec): 206.842 > > >> >> >>> Stddev Bandwidth: 8.10412 > > >> >> >>> Max bandwidth (MB/sec): 224 > > >> >> >>> Min bandwidth (MB/sec): 180 > > >> >> >>> Average IOPS: 51 > > >> >> >>> Stddev IOPS: 2 > > >> >> >>> Max IOPS: 56 > > >> >> >>> Min IOPS: 45 > > >> >> >>> Average Latency(s): 0.0193366 > > >> >> >>> Stddev Latency(s): 0.00148039 > > >> >> >>> Max latency(s): 0.0377946 > > >> >> >>> Min latency(s): 0.015909 > > >> >> >>> > > >> >> >>> Nick > > >> >> >>> > > >> >> >>>> -----Original Message----- > > >> >> >>>> From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] > > >> >> >>>> On Behalf Of Horace > > >> >> >>>> Sent: 21 July 2016 10:26 > > >> >> >>>> To: wr@xxxxxxxx > > >> >> >>>> Cc: ceph-users@xxxxxxxxxxxxxx > > >> >> >>>> Subject: Re: Ceph + VMware + Single Thread > > >> >> >>>> Performance > > >> >> >>>> > > >> >> >>>> Hi, > > >> >> >>>> > > >> >> >>>> Same here, I've read some blog saying that vmware will > > >> >> >>>> frequently verify the locking on VMFS over iSCSI, hence it > > >> >> >>>> will have much slower performance than NFS (with different > > >> locking mechanism). > > >> >> >>>> > > >> >> >>>> Regards, > > >> >> >>>> Horace Ng > > >> >> >>>> > > >> >> >>>> ----- Original Message ----- > > >> >> >>>> From: wr@xxxxxxxx > > >> >> >>>> To: ceph-users@xxxxxxxxxxxxxx > > >> >> >>>> Sent: Thursday, July 21, 2016 5:11:21 PM > > >> >> >>>> Subject: Ceph + VMware + Single Thread > > >> >> >>>> Performance > > >> >> >>>> > > >> >> >>>> Hi everyone, > > >> >> >>>> > > >> >> >>>> we see at our cluster relatively slow Single Thread Performance on the iscsi Nodes. > > >> >> >>>> > > >> >> >>>> > > >> >> >>>> Our setup: > > >> >> >>>> > > >> >> >>>> 3 Racks: > > >> >> >>>> > > >> >> >>>> 18x Data Nodes, 3 Mon Nodes, 3 iscsi Gateway Nodes with tgt (rbd cache off). > > >> >> >>>> > > >> >> >>>> 2x Samsung SM863 Enterprise SSD for Journal (3 OSD per SSD) > > >> >> >>>> and 6x WD Red 1TB per Data Node as OSD. > > >> >> >>>> > > >> >> >>>> Replication = 3 > > >> >> >>>> > > >> >> >>>> chooseleaf = 3 type Rack in the crush map > > >> >> >>>> > > >> >> >>>> > > >> >> >>>> We get only ca. 90 MByte/s on the iscsi Gateway Servers with: > > >> >> >>>> > > >> >> >>>> rados bench -p rbd 60 write -b 4M -t 1 > > >> >> >>>> > > >> >> >>>> > > >> >> >>>> If we test with: > > >> >> >>>> > > >> >> >>>> rados bench -p rbd 60 write -b 4M -t 32 > > >> >> >>>> > > >> >> >>>> we get ca. 600 - 700 MByte/s > > >> >> >>>> > > >> >> >>>> > > >> >> >>>> We plan to replace the Samsung SSD with Intel DC P3700 PCIe > > >> >> >>>> NVM'e for the Journal to get better Single Thread Performance. > > >> >> >>>> > > >> >> >>>> Is anyone of you out there who has an Intel P3700 for > > >> >> >>>> Journal an can give me back test results with: > > >> >> >>>> > > >> >> >>>> > > >> >> >>>> rados bench -p rbd 60 write -b 4M -t 1 > > >> >> >>>> > > >> >> >>>> > > >> >> >>>> Thank you very much !! > > >> >> >>>> > > >> >> >>>> Kind Regards !! > > >> >> >>>> > > >> >> >>>> _______________________________________________ > > >> >> >>>> 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 > > >> >> >> _______________________________________________ > > >> >> >> 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 > > > > > > _______________________________________________ > > > 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 > > > > > -- > 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 _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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