I want to provide an update to my interesting situation. (New storage nodes were purchased and are going into the cluster soon)
I have been monitoring the ceph storage nodes with atop and read/write through put with ceph-dash for the last month. I am regularly seeing 80-90MB/s of write throughput (140MB/s read) on the ceph cluster. At these moments, the problem ceph node I have been speaking of shows 101% disk busy on the same 3 to 4 (of the 9) OSDs. So I am getting the throughput that I want with on the cluster, despite the OSDs in question. However, when I run the bench tests described in this thread, I do not see the write throughput go above 5MB/s. When I take the problem node out, and run the bench tests, I see the throughput double, but not over 10MB/s. Why is the ceph cluster getting up to 90MB/s write in the wild, but not when running the bench tests ? -RG On Fri, Oct 27, 2017 at 4:21 PM, Russell Glaue <rgl...@cait.org> wrote: > Yes, several have recommended the fio test now. > I cannot perform a fio test at this time. Because the post referred to > directs us to write the fio test data directly to the disk device, e.g. > /dev/sdj. I'd have to take an OSD completely out in order to perform the > test. And I am not ready to do that at this time. Perhaps after I attempt > the hardware firmware updates, and still do not have an answer, I would > then take an OSD out of the cluster to run the fio test. > Also, our M500 disks on the two newest machines are all running version > MU05, the latest firmware. The on the older two, they are behind a RAID0, > but I suspect they might be MU03 firmware. > -RG > > > On Fri, Oct 27, 2017 at 4:12 PM, Brian Andrus <brian.and...@dreamhost.com> > wrote: > >> I would be interested in seeing the results from the post mentioned by an >> earlier contributor: >> >> https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-tes >> t-if-your-ssd-is-suitable-as-a-journal-device/ >> >> Test an "old" M500 and a "new" M500 and see if the performance is A) >> acceptable and B) comparable. Find hardware revision or firmware revision >> in case of A=Good and B=different. >> >> If the "old" device doesn't test well in fio/dd testing, then the drives >> are (as expected) not a great choice for journals and you might want to >> look at hardware/backplane/RAID configuration differences that are somehow >> allowing them to perform adequately. >> >> On Fri, Oct 27, 2017 at 12:36 PM, Russell Glaue <rgl...@cait.org> wrote: >> >>> Yes, all the MD500s we use are both journal and OSD, even the older >>> ones. We have a 3 year lifecycle and move older nodes from one ceph cluster >>> to another. >>> On old systems with 3 year old MD500s, they run as RAID0, and run faster >>> than our current problem system with 1 year old MD500s, ran as nonraid >>> pass-through on the controller. >>> >>> All disks are SATA and are connected to a SAS controller. We were >>> wondering if the SAS/SATA conversion is an issue. Yet, the older systems >>> don't exhibit a problem. >>> >>> I found what I wanted to know from a colleague, that when the current >>> ceph cluster was put together, the SSDs tested at 300+MB/s, and ceph >>> cluster writes at 30MB/s. >>> >>> Using SMART tools, the reserved cells in all drives is nearly 100%. >>> >>> Restarting the OSDs minorly improved performance. Still betting on >>> hardware issues that a firmware upgrade may resolve. >>> >>> -RG >>> >>> >>> On Oct 27, 2017 1:14 PM, "Brian Andrus" <brian.and...@dreamhost.com> >>> wrote: >>> >>> @Russel, are your "older Crucial M500"s being used as journals? >>> >>> Crucial M500s are not to be used as a Ceph journal in my last experience >>> with them. They make good OSDs with an NVMe in front of them perhaps, but >>> not much else. >>> >>> Ceph uses O_DSYNC for journal writes and these drives do not handle them >>> as expected. It's been many years since I've dealt with the M500s >>> specifically, but it has to do with the capacitor/power save feature and >>> how it handles those types of writes. I'm sorry I don't have the emails >>> with specifics around anymore, but last I remember, this was a hardware >>> issue and could not be resolved with firmware. >>> >>> Paging Kyle Bader... >>> >>> On Fri, Oct 27, 2017 at 9:24 AM, Russell Glaue <rgl...@cait.org> wrote: >>> >>>> We have older crucial M500 disks operating without such problems. So, I >>>> have to believe it is a hardware firmware issue. >>>> And its peculiar seeing performance boost slightly, even 24 hours >>>> later, when I stop then start the OSDs. >>>> >>>> Our actual writes are low, as most of our Ceph Cluster based images are >>>> low-write, high-memory. So a 20GB/day life/write capacity is a non-issue >>>> for us. Only write speed is the concern. Our write-intensive images are >>>> locked on non-ceph disks. >>>> >>>> What are others using for SSD drives in their Ceph cluster? >>>> With 0.50+ DWPD (Drive Writes Per Day), the Kingston SEDC400S37 models >>>> seems to be the best for the price today. >>>> >>>> >>>> >>>> On Fri, Oct 27, 2017 at 6:34 AM, Maged Mokhtar <mmokh...@petasan.org> >>>> wrote: >>>> >>>>> It is quiet likely related, things are pointing to bad disks. Probably >>>>> the best thing is to plan for disk replacement, the sooner the better as >>>>> it >>>>> could get worse. >>>>> >>>>> >>>>> >>>>> On 2017-10-27 02:22, Christian Wuerdig wrote: >>>>> >>>>> Hm, no necessarily directly related to your performance problem, >>>>> however: These SSDs have a listed endurance of 72TB total data written >>>>> - over a 5 year period that's 40GB a day or approx 0.04 DWPD. Given >>>>> that you run the journal for each OSD on the same disk, that's >>>>> effectively at most 0.02 DWPD (about 20GB per day per disk). I don't >>>>> know many who'd run a cluster on disks like those. Also it means these >>>>> are pure consumer drives which have a habit of exhibiting random >>>>> performance at times (based on unquantified anecdotal personal >>>>> experience with other consumer model SSDs). I wouldn't touch these >>>>> with a long stick for anything but small toy-test clusters. >>>>> >>>>> On Fri, Oct 27, 2017 at 3:44 AM, Russell Glaue <rgl...@cait.org> >>>>> wrote: >>>>> >>>>> >>>>> On Wed, Oct 25, 2017 at 7:09 PM, Maged Mokhtar <mmokh...@petasan.org> >>>>> wrote: >>>>> >>>>> >>>>> It depends on what stage you are in: >>>>> in production, probably the best thing is to setup a monitoring tool >>>>> (collectd/grahite/prometheus/grafana) to monitor both ceph stats as >>>>> well as >>>>> resource load. This will, among other things, show you if you have >>>>> slowing >>>>> disks. >>>>> >>>>> >>>>> I am monitoring Ceph performance with ceph-dash >>>>> (http://cephdash.crapworks.de/), that is why I knew to look into the >>>>> slow >>>>> writes issue. And I am using Monitorix (http://www.monitorix.org/) to >>>>> monitor system resources, including Disk I/O. >>>>> >>>>> However, though I can monitor individual disk performance at the system >>>>> level, it seems Ceph does not tax any disk more than the worst disk. >>>>> So in >>>>> my monitoring charts, all disks have the same performance. >>>>> All four nodes are base-lining at 50 writes/sec during the cluster's >>>>> normal >>>>> load, with the non-problem hosts spiking up to 150, and the problem >>>>> host >>>>> only spikes up to 100. >>>>> But during the window of time I took the problem host OSDs down to run >>>>> the >>>>> bench tests, the OSDs on the other nodes increased to 300-500 >>>>> writes/sec. >>>>> Otherwise, the chart looks the same for all disks on all ceph >>>>> nodes/hosts. >>>>> >>>>> Before production you should first make sure your SSDs are suitable for >>>>> Ceph, either by being recommend by other Ceph users or you test them >>>>> yourself for sync writes performance using fio tool as outlined >>>>> earlier. >>>>> Then after you build your cluster you can use rados and/or rbd bencmark >>>>> tests to benchmark your cluster and find bottlenecks using >>>>> atop/sar/collectl >>>>> which will help you tune your cluster. >>>>> >>>>> >>>>> All 36 OSDs are: Crucial_CT960M500SSD1 >>>>> >>>>> Rados bench tests were done at the beginning. The speed was much >>>>> faster than >>>>> it is now. I cannot recall the test results, someone else on my team >>>>> ran >>>>> them. Recently, I had thought the slow disk problem was a configuration >>>>> issue with Ceph - before I posted here. Now we are hoping it may be >>>>> resolved >>>>> with a firmware update. (If it is firmware related, rebooting the >>>>> problem >>>>> node may temporarily resolve this) >>>>> >>>>> >>>>> Though you did see better improvements, your cluster with 27 SSDs >>>>> should >>>>> give much higher numbers than 3k iops. If you are running rados bench >>>>> while >>>>> you have other client ios, then obviously the reported number by the >>>>> tool >>>>> will be less than what the cluster is actually giving...which you can >>>>> find >>>>> out via ceph status command, it will print the total cluster >>>>> throughput and >>>>> iops. If the total is still low i would recommend running the fio raw >>>>> disk >>>>> test, maybe the disks are not suitable. When you removed your 9 bad >>>>> disk >>>>> from 36 and your performance doubled, you still had 2 other disk >>>>> slowing >>>>> you..meaning near 100% busy ? It makes me feel the disk type used is >>>>> not >>>>> good. For these near 100% busy disks can you also measure their raw >>>>> disk >>>>> iops at that load (i am not sure atop shows this, if not use >>>>> sat/syssyat/iostat/collecl). >>>>> >>>>> >>>>> I ran another bench test today with all 36 OSDs up. The overall >>>>> performance >>>>> was improved slightly compared to the original tests. Only 3 OSDs on >>>>> the >>>>> problem host were increasing to 101% disk busy. >>>>> The iops reported from ceph status during this bench test ranged from >>>>> 1.6k >>>>> to 3.3k, the test yielding 4k iops. >>>>> >>>>> Yes, the two other OSDs/disks that were the bottleneck were at 101% >>>>> disk >>>>> busy. The other OSD disks on the same host were sailing along at like >>>>> 50-60% >>>>> busy. >>>>> >>>>> All 36 OSD disks are exactly the same disk. They were all purchased at >>>>> the >>>>> same time. All were installed at the same time. >>>>> I cannot believe it is a problem with the disk model. A failed/bad >>>>> disk, >>>>> perhaps is possible. But the disk model itself cannot be the problem >>>>> based >>>>> on what I am seeing. If I am seeing bad performance on all disks on >>>>> one ceph >>>>> node/host, but not on another ceph node with these same disks, it has >>>>> to be >>>>> some other factor. This is why I am now guessing a firmware upgrade is >>>>> needed. >>>>> >>>>> Also, as I eluded to here earlier. I took down all 9 OSDs in the >>>>> problem >>>>> host yesterday to run the bench test. >>>>> Today, with those 9 OSDs back online, I rerun the bench test, I am see >>>>> 2-3 >>>>> OSD disks with 101% busy on the problem host, and the other disks are >>>>> lower >>>>> than 80%. So, for whatever reason, shutting down the OSDs and starting >>>>> them >>>>> back up, allowed many (not all) of the OSDs performance to improve on >>>>> the >>>>> problem host. >>>>> >>>>> >>>>> Maged >>>>> >>>>> On 2017-10-25 23:44, Russell Glaue wrote: >>>>> >>>>> Thanks to all. >>>>> I took the OSDs down in the problem host, without shutting down the >>>>> machine. >>>>> As predicted, our MB/s about doubled. >>>>> Using this bench/atop procedure, I found two other OSDs on another host >>>>> that are the next bottlenecks. >>>>> >>>>> Is this the only good way to really test the performance of the drives >>>>> as >>>>> OSDs? Is there any other way? >>>>> >>>>> While running the bench on all 36 OSDs, the 9 problem OSDs stuck out. >>>>> But >>>>> two new problem OSDs I just discovered in this recent test of 27 OSDs >>>>> did >>>>> not stick out at all. Because ceph bench distributes the load making >>>>> only >>>>> the very worst denominators show up in atop. So ceph is a slow as your >>>>> slowest drive. >>>>> >>>>> It would be really great if I could run the bench test, and some how >>>>> get >>>>> the bench to use only certain OSDs during the test. Then I could run >>>>> the >>>>> test, avoiding the OSDs that I already know is a problem, so I can >>>>> find the >>>>> next worst OSD. >>>>> >>>>> >>>>> [ the bench test ] >>>>> rados bench -p scbench -b 4096 30 write -t 32 >>>>> >>>>> [ original results with all 36 OSDs ] >>>>> Total time run: 30.822350 >>>>> Total writes made: 31032 >>>>> Write size: 4096 >>>>> Object size: 4096 >>>>> Bandwidth (MB/sec): 3.93282 >>>>> Stddev Bandwidth: 3.66265 >>>>> Max bandwidth (MB/sec): 13.668 >>>>> Min bandwidth (MB/sec): 0 >>>>> Average IOPS: 1006 >>>>> Stddev IOPS: 937 >>>>> Max IOPS: 3499 >>>>> Min IOPS: 0 >>>>> Average Latency(s): 0.0317779 >>>>> Stddev Latency(s): 0.164076 >>>>> Max latency(s): 2.27707 >>>>> Min latency(s): 0.0013848 >>>>> Cleaning up (deleting benchmark objects) >>>>> Clean up completed and total clean up time :20.166559 >>>>> >>>>> [ after stopping all of the OSDs (9) on the problem host ] >>>>> Total time run: 32.586830 >>>>> Total writes made: 59491 >>>>> Write size: 4096 >>>>> Object size: 4096 >>>>> Bandwidth (MB/sec): 7.13131 >>>>> Stddev Bandwidth: 9.78725 >>>>> Max bandwidth (MB/sec): 29.168 >>>>> Min bandwidth (MB/sec): 0 >>>>> Average IOPS: 1825 >>>>> Stddev IOPS: 2505 >>>>> Max IOPS: 7467 >>>>> Min IOPS: 0 >>>>> Average Latency(s): 0.0173691 >>>>> Stddev Latency(s): 0.21634 >>>>> Max latency(s): 6.71283 >>>>> Min latency(s): 0.00107473 >>>>> Cleaning up (deleting benchmark objects) >>>>> Clean up completed and total clean up time :16.269393 >>>>> >>>>> >>>>> >>>>> On Fri, Oct 20, 2017 at 1:35 PM, Russell Glaue <rgl...@cait.org> >>>>> wrote: >>>>> >>>>> >>>>> On the machine in question, the 2nd newest, we are using the LSI >>>>> MegaRAID >>>>> SAS-3 3008 [Fury], which allows us a "Non-RAID" option, and has no >>>>> battery. >>>>> The older two use the LSI MegaRAID SAS 2208 [Thunderbolt] I reported >>>>> earlier, each single drive configured as RAID0. >>>>> >>>>> Thanks for everyone's help. >>>>> I am going to run a 32 thread bench test after taking the 2nd machine >>>>> out >>>>> of the cluster with noout. >>>>> After it is out of the cluster, I am expecting the slow write issue >>>>> will >>>>> not surface. >>>>> >>>>> >>>>> On Fri, Oct 20, 2017 at 5:27 AM, David Turner <drakonst...@gmail.com> >>>>> wrote: >>>>> >>>>> >>>>> I can attest that the battery in the raid controller is a thing. I'm >>>>> used to using lsi controllers, but my current position has hp raid >>>>> controllers and we just tracked down 10 of our nodes that had >100ms >>>>> await >>>>> pretty much always were the only 10 nodes in the cluster with failed >>>>> batteries on the raid controllers. >>>>> >>>>> >>>>> On Thu, Oct 19, 2017, 8:15 PM Christian Balzer <ch...@gol.com> wrote: >>>>> >>>>> >>>>> >>>>> Hello, >>>>> >>>>> On Thu, 19 Oct 2017 17:14:17 -0500 Russell Glaue wrote: >>>>> >>>>> That is a good idea. >>>>> However, a previous rebalancing processes has brought performance of >>>>> our >>>>> Guest VMs to a slow drag. >>>>> >>>>> >>>>> Never mind that I'm not sure that these SSDs are particular well suited >>>>> for Ceph, your problem is clearly located on that one node. >>>>> >>>>> Not that I think it's the case, but make sure your PG distribution is >>>>> not >>>>> skewed with many more PGs per OSD on that node. >>>>> >>>>> Once you rule that out my first guess is the RAID controller, you're >>>>> running the SSDs are single RAID0s I presume? >>>>> If so a either configuration difference or a failed BBU on the >>>>> controller >>>>> could result in the writeback cache being disabled, which would explain >>>>> things beautifully. >>>>> >>>>> As for a temporary test/fix (with reduced redundancy of course), set >>>>> noout >>>>> (or mon_osd_down_out_subtree_limit accordingly) and turn the slow host >>>>> off. >>>>> >>>>> This should result in much better performance than you have now and of >>>>> course be the final confirmation of that host being the culprit. >>>>> >>>>> Christian >>>>> >>>>> >>>>> On Thu, Oct 19, 2017 at 3:55 PM, Jean-Charles Lopez >>>>> <jelo...@redhat.com> >>>>> wrote: >>>>> >>>>> Hi Russell, >>>>> >>>>> as you have 4 servers, assuming you are not doing EC pools, just >>>>> stop all >>>>> the OSDs on the second questionable server, mark the OSDs on that >>>>> server as >>>>> out, let the cluster rebalance and when all PGs are active+clean >>>>> just >>>>> replay the test. >>>>> >>>>> All IOs should then go only to the other 3 servers. >>>>> >>>>> JC >>>>> >>>>> On Oct 19, 2017, at 13:49, Russell Glaue <rgl...@cait.org> wrote: >>>>> >>>>> No, I have not ruled out the disk controller and backplane making >>>>> the >>>>> disks slower. >>>>> Is there a way I could test that theory, other than swapping out >>>>> hardware? >>>>> -RG >>>>> >>>>> On Thu, Oct 19, 2017 at 3:44 PM, David Turner >>>>> <drakonst...@gmail.com> >>>>> wrote: >>>>> >>>>> Have you ruled out the disk controller and backplane in the server >>>>> running slower? >>>>> >>>>> On Thu, Oct 19, 2017 at 4:42 PM Russell Glaue <rgl...@cait.org> >>>>> wrote: >>>>> >>>>> I ran the test on the Ceph pool, and ran atop on all 4 storage >>>>> servers, >>>>> as suggested. >>>>> >>>>> Out of the 4 servers: >>>>> 3 of them performed with 17% to 30% disk %busy, and 11% CPU wait. >>>>> Momentarily spiking up to 50% on one server, and 80% on another >>>>> The 2nd newest server was almost averaging 90% disk %busy and >>>>> 150% CPU >>>>> wait. And more than momentarily spiking to 101% disk busy and >>>>> 250% CPU wait. >>>>> For this 2nd newest server, this was the statistics for about 8 >>>>> of 9 >>>>> disks, with the 9th disk not far behind the others. >>>>> >>>>> I cannot believe all 9 disks are bad >>>>> They are the same disks as the newest 1st server, >>>>> Crucial_CT960M500SSD1, >>>>> and same exact server hardware too. >>>>> They were purchased at the same time in the same purchase order >>>>> and >>>>> arrived at the same time. >>>>> So I cannot believe I just happened to put 9 bad disks in one >>>>> server, >>>>> and 9 good ones in the other. >>>>> >>>>> I know I have Ceph configured exactly the same on all servers >>>>> And I am sure I have the hardware settings configured exactly the >>>>> same >>>>> on the 1st and 2nd servers. >>>>> So if I were someone else, I would say it maybe is bad hardware >>>>> on the >>>>> 2nd server. >>>>> But the 2nd server is running very well without any hint of a >>>>> problem. >>>>> >>>>> Any other ideas or suggestions? >>>>> >>>>> -RG >>>>> >>>>> >>>>> On Wed, Oct 18, 2017 at 3:40 PM, Maged Mokhtar >>>>> <mmokh...@petasan.org> >>>>> wrote: >>>>> >>>>> just run the same 32 threaded rados test as you did before and >>>>> this >>>>> time run atop while the test is running looking for %busy of >>>>> cpu/disks. It >>>>> should give an idea if there is a bottleneck in them. >>>>> >>>>> On 2017-10-18 21:35, Russell Glaue wrote: >>>>> >>>>> I cannot run the write test reviewed at the >>>>> ceph-how-to-test-if-your-s >>>>> sd-is-suitable-as-a-journal-device blog. The tests write >>>>> directly to >>>>> the raw disk device. >>>>> Reading an infile (created with urandom) on one SSD, writing the >>>>> outfile to another osd, yields about 17MB/s. >>>>> But Isn't this write speed limited by the speed in which in the >>>>> dd >>>>> infile can be read? >>>>> And I assume the best test should be run with no other load. >>>>> >>>>> How does one run the rados bench "as stress"? >>>>> >>>>> -RG >>>>> >>>>> >>>>> On Wed, Oct 18, 2017 at 1:33 PM, Maged Mokhtar >>>>> <mmokh...@petasan.org> >>>>> wrote: >>>>> >>>>> measuring resource load as outlined earlier will show if the >>>>> drives >>>>> are performing well or not. Also how many osds do you have ? >>>>> >>>>> On 2017-10-18 19:26, Russell Glaue wrote: >>>>> >>>>> The SSD drives are Crucial M500 >>>>> A Ceph user did some benchmarks and found it had good >>>>> performance >>>>> https://forum.proxmox.com/threads/ceph-bad-performance-in- >>>>> qemu-guests.21551/ >>>>> >>>>> However, a user comment from 3 years ago on the blog post you >>>>> linked >>>>> to says to avoid the Crucial M500 >>>>> >>>>> Yet, this performance posting tells that the Crucial M500 is >>>>> good. >>>>> https://inside.servers.com/ssd-performance-2017-c4307a92dea >>>>> >>>>> On Wed, Oct 18, 2017 at 11:53 AM, Maged Mokhtar >>>>> <mmokh...@petasan.org> >>>>> wrote: >>>>> >>>>> Check out the following link: some SSDs perform bad in Ceph >>>>> due to >>>>> sync writes to journal >>>>> >>>>> https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-tes >>>>> t-if-your-ssd-is-suitable-as-a-journal-device/ >>>>> >>>>> Anther thing that can help is to re-run the rados 32 threads >>>>> as >>>>> stress and view resource usage using atop (or collectl/sar) to >>>>> check for >>>>> %busy cpu and %busy disks to give you an idea of what is >>>>> holding down your >>>>> cluster..for example: if cpu/disk % are all low then check >>>>> your >>>>> network/switches. If disk %busy is high (90%) for all disks >>>>> then your >>>>> disks are the bottleneck: which either means you have SSDs >>>>> that are not >>>>> suitable for Ceph or you have too few disks (which i doubt is >>>>> the case). If >>>>> only 1 disk %busy is high, there may be something wrong with >>>>> this disk >>>>> should be removed. >>>>> >>>>> Maged >>>>> >>>>> On 2017-10-18 18:13, Russell Glaue wrote: >>>>> >>>>> In my previous post, in one of my points I was wondering if >>>>> the >>>>> request size would increase if I enabled jumbo packets. >>>>> currently it is >>>>> disabled. >>>>> >>>>> @jdillama: The qemu settings for both these two guest >>>>> machines, with >>>>> RAID/LVM and Ceph/rbd images, are the same. I am not thinking >>>>> that changing >>>>> the qemu settings of "min_io_size=<limited to >>>>> 16bits>,opt_io_size=<RBD >>>>> image object size>" will directly address the issue. >>>>> >>>>> @mmokhtar: Ok. So you suggest the request size is the result >>>>> of the >>>>> problem and not the cause of the problem. meaning I should go >>>>> after a >>>>> different issue. >>>>> >>>>> I have been trying to get write speeds up to what people on >>>>> this mail >>>>> list are discussing. >>>>> It seems that for our configuration, as it matches others, we >>>>> should >>>>> be getting about 70MB/s write speed. >>>>> But we are not getting that. >>>>> Single writes to disk are lucky to get 5MB/s to 6MB/s, but are >>>>> typically 1MB/s to 2MB/s. >>>>> Monitoring the entire Ceph cluster (using >>>>> http://cephdash.crapworks.de/), I have seen very rare >>>>> momentary >>>>> spikes up to 30MB/s. >>>>> >>>>> My storage network is connected via a 10Gb switch >>>>> I have 4 storage servers with a LSI Logic MegaRAID SAS 2208 >>>>> controller >>>>> Each storage server has 9 1TB SSD drives, each drive as 1 osd >>>>> (no >>>>> RAID) >>>>> Each drive is one LVM group, with two volumes - one volume for >>>>> the >>>>> osd, one volume for the journal >>>>> Each osd is formatted with xfs >>>>> The crush map is simple: default->rack->[host[1..4]->osd] with >>>>> an >>>>> evenly distributed weight >>>>> The redundancy is triple replication >>>>> >>>>> While I have read comments that having the osd and journal on >>>>> the >>>>> same disk decreases write speed, I have also read that once >>>>> past 8 OSDs per >>>>> node this is the recommended configuration, however this is >>>>> also the reason >>>>> why SSD drives are used exclusively for OSDs in the storage >>>>> nodes. >>>>> None-the-less, I was still expecting write speeds to be above >>>>> 30MB/s, >>>>> not below 6MB/s. >>>>> Even at 12x slower than the RAID, using my previously posted >>>>> iostat >>>>> data set, I should be seeing write speeds that average 10MB/s, >>>>> not 2MB/s. >>>>> >>>>> In regards to the rados benchmark tests you asked me to run, >>>>> here is >>>>> the output: >>>>> >>>>> [centos7]# rados bench -p scbench -b 4096 30 write -t 1 >>>>> Maintaining 1 concurrent writes of 4096 bytes to objects of >>>>> size 4096 >>>>> for up to 30 seconds or 0 objects >>>>> Object prefix: benchmark_data_hamms.sys.cu.cait.org_85049 >>>>> sec Cur ops started finished avg MB/s cur MB/s last >>>>> lat(s) >>>>> avg lat(s) >>>>> 0 0 0 0 0 0 >>>>> - >>>>> 0 >>>>> 1 1 201 200 0.78356 0.78125 >>>>> 0.00522307 >>>>> 0.00496574 >>>>> 2 1 469 468 0.915303 1.04688 >>>>> 0.00437497 >>>>> 0.00426141 >>>>> 3 1 741 740 0.964371 1.0625 >>>>> 0.00512853 >>>>> 0.0040434 >>>>> 4 1 888 887 0.866739 0.574219 >>>>> 0.00307699 >>>>> 0.00450177 >>>>> 5 1 1147 1146 0.895725 1.01172 >>>>> 0.00376454 >>>>> 0.0043559 >>>>> 6 1 1325 1324 0.862293 0.695312 >>>>> 0.00459443 >>>>> 0.004525 >>>>> 7 1 1494 1493 0.83339 0.660156 >>>>> 0.00461002 >>>>> 0.00458452 >>>>> 8 1 1736 1735 0.847369 0.945312 >>>>> 0.00253971 >>>>> 0.00460458 >>>>> 9 1 1998 1997 0.866922 1.02344 >>>>> 0.00236573 >>>>> 0.00450172 >>>>> 10 1 2260 2259 0.882563 1.02344 >>>>> 0.00262179 >>>>> 0.00442152 >>>>> 11 1 2526 2525 0.896775 1.03906 >>>>> 0.00336914 >>>>> 0.00435092 >>>>> 12 1 2760 2759 0.898203 0.914062 >>>>> 0.00351827 >>>>> 0.00434491 >>>>> 13 1 3016 3015 0.906025 1 >>>>> 0.00335703 >>>>> 0.00430691 >>>>> 14 1 3257 3256 0.908545 0.941406 >>>>> 0.00332344 >>>>> 0.00429495 >>>>> 15 1 3490 3489 0.908644 0.910156 >>>>> 0.00318815 >>>>> 0.00426387 >>>>> 16 1 3728 3727 0.909952 0.929688 >>>>> 0.0032881 >>>>> 0.00428895 >>>>> 17 1 3986 3985 0.915703 1.00781 >>>>> 0.00274809 >>>>> 0.0042614 >>>>> 18 1 4250 4249 0.922116 1.03125 >>>>> 0.00287411 >>>>> 0.00423214 >>>>> 19 1 4505 4504 0.926003 0.996094 >>>>> 0.00375435 >>>>> 0.00421442 >>>>> 2017-10-18 10:56:31.267173 min lat: 0.00181259 max lat: >>>>> 0.270553 avg >>>>> lat: 0.00420118 >>>>> sec Cur ops started finished avg MB/s cur MB/s last >>>>> lat(s) >>>>> avg lat(s) >>>>> 20 1 4757 4756 0.928915 0.984375 >>>>> 0.00463972 >>>>> 0.00420118 >>>>> 21 1 5009 5008 0.93155 0.984375 >>>>> 0.00360065 >>>>> 0.00418937 >>>>> 22 1 5235 5234 0.929329 0.882812 >>>>> 0.00626214 >>>>> 0.004199 >>>>> 23 1 5500 5499 0.933925 1.03516 >>>>> 0.00466584 >>>>> 0.00417836 >>>>> 24 1 5708 5707 0.928861 0.8125 >>>>> 0.00285727 >>>>> 0.00420146 >>>>> 25 0 5964 5964 0.931858 1.00391 >>>>> 0.00417383 >>>>> 0.0041881 >>>>> 26 1 6216 6215 0.933722 0.980469 >>>>> 0.0041009 >>>>> 0.00417915 >>>>> 27 1 6481 6480 0.937474 1.03516 >>>>> 0.00307484 >>>>> 0.00416118 >>>>> 28 1 6745 6744 0.940819 1.03125 >>>>> 0.00266329 >>>>> 0.00414777 >>>>> 29 1 7003 7002 0.943124 1.00781 >>>>> 0.00305905 >>>>> 0.00413758 >>>>> 30 1 7271 7270 0.946578 1.04688 >>>>> 0.00391017 >>>>> 0.00412238 >>>>> Total time run: 30.006060 >>>>> Total writes made: 7272 >>>>> Write size: 4096 >>>>> Object size: 4096 >>>>> Bandwidth (MB/sec): 0.946684 >>>>> Stddev Bandwidth: 0.123762 >>>>> Max bandwidth (MB/sec): 1.0625 >>>>> Min bandwidth (MB/sec): 0.574219 >>>>> Average IOPS: 242 >>>>> Stddev IOPS: 31 >>>>> Max IOPS: 272 >>>>> Min IOPS: 147 >>>>> Average Latency(s): 0.00412247 >>>>> Stddev Latency(s): 0.00648437 >>>>> Max latency(s): 0.270553 >>>>> Min latency(s): 0.00175318 >>>>> Cleaning up (deleting benchmark objects) >>>>> Clean up completed and total clean up time :29.069423 >>>>> >>>>> [centos7]# rados bench -p scbench -b 4096 30 write -t 32 >>>>> Maintaining 32 concurrent writes of 4096 bytes to objects of >>>>> size >>>>> 4096 for up to 30 seconds or 0 objects >>>>> Object prefix: benchmark_data_hamms.sys.cu.cait.org_86076 >>>>> sec Cur ops started finished avg MB/s cur MB/s last >>>>> lat(s) >>>>> avg lat(s) >>>>> 0 0 0 0 0 0 >>>>> - >>>>> 0 >>>>> 1 32 3013 2981 11.6438 11.6445 >>>>> 0.00247906 >>>>> 0.00572026 >>>>> 2 32 5349 5317 10.3834 9.125 >>>>> 0.00246662 >>>>> 0.00932016 >>>>> 3 32 5707 5675 7.3883 1.39844 >>>>> 0.00389774 >>>>> 0.0156726 >>>>> 4 32 5895 5863 5.72481 0.734375 >>>>> 1.13137 >>>>> 0.0167946 >>>>> 5 32 6869 6837 5.34068 3.80469 >>>>> 0.0027652 >>>>> 0.0226577 >>>>> 6 32 8901 8869 5.77306 7.9375 >>>>> 0.0053211 >>>>> 0.0216259 >>>>> 7 32 10800 10768 6.00785 7.41797 >>>>> 0.00358187 >>>>> 0.0207418 >>>>> 8 32 11825 11793 5.75728 4.00391 >>>>> 0.00217575 >>>>> 0.0215494 >>>>> 9 32 12941 12909 5.6019 4.35938 >>>>> 0.00278512 >>>>> 0.0220567 >>>>> 10 32 13317 13285 5.18849 1.46875 >>>>> 0.0034973 >>>>> 0.0240665 >>>>> 11 32 16189 16157 5.73653 11.2188 >>>>> 0.00255841 >>>>> 0.0212708 >>>>> 12 32 16749 16717 5.44077 2.1875 >>>>> 0.00330334 >>>>> 0.0215915 >>>>> 13 32 16756 16724 5.02436 0.0273438 >>>>> 0.00338994 >>>>> 0.021849 >>>>> 14 32 17908 17876 4.98686 4.5 >>>>> 0.00402598 >>>>> 0.0244568 >>>>> 15 32 17936 17904 4.66171 0.109375 >>>>> 0.00375799 >>>>> 0.0245545 >>>>> 16 32 18279 18247 4.45409 1.33984 >>>>> 0.00483873 >>>>> 0.0267929 >>>>> 17 32 18372 18340 4.21346 0.363281 >>>>> 0.00505187 >>>>> 0.0275887 >>>>> 18 32 19403 19371 4.20309 4.02734 >>>>> 0.00545154 >>>>> 0.029348 >>>>> 19 31 19845 19814 4.07295 1.73047 >>>>> 0.00254726 >>>>> 0.0306775 >>>>> 2017-10-18 10:57:58.160536 min lat: 0.0015005 max lat: 2.27707 >>>>> avg >>>>> lat: 0.0307559 >>>>> sec Cur ops started finished avg MB/s cur MB/s last >>>>> lat(s) >>>>> avg lat(s) >>>>> 20 31 20401 20370 3.97788 2.17188 >>>>> 0.00307238 >>>>> 0.0307559 >>>>> 21 32 21338 21306 3.96254 3.65625 >>>>> 0.00464563 >>>>> 0.0312288 >>>>> 22 32 23057 23025 4.0876 6.71484 >>>>> 0.00296295 >>>>> 0.0299267 >>>>> 23 32 23057 23025 3.90988 0 >>>>> - >>>>> 0.0299267 >>>>> 24 32 23803 23771 3.86837 1.45703 >>>>> 0.00301471 >>>>> 0.0312804 >>>>> 25 32 24112 24080 3.76191 1.20703 >>>>> 0.00191063 >>>>> 0.0331462 >>>>> 26 31 25303 25272 3.79629 4.65625 >>>>> 0.00794399 >>>>> 0.0329129 >>>>> 27 32 28803 28771 4.16183 13.668 >>>>> 0.0109817 >>>>> 0.0297469 >>>>> 28 32 29592 29560 4.12325 3.08203 >>>>> 0.00188185 >>>>> 0.0301911 >>>>> 29 32 30595 30563 4.11616 3.91797 >>>>> 0.00379099 >>>>> 0.0296794 >>>>> 30 32 31031 30999 4.03572 1.70312 >>>>> 0.00283347 >>>>> 0.0302411 >>>>> Total time run: 30.822350 >>>>> Total writes made: 31032 >>>>> Write size: 4096 >>>>> Object size: 4096 >>>>> Bandwidth (MB/sec): 3.93282 >>>>> Stddev Bandwidth: 3.66265 >>>>> Max bandwidth (MB/sec): 13.668 >>>>> Min bandwidth (MB/sec): 0 >>>>> Average IOPS: 1006 >>>>> Stddev IOPS: 937 >>>>> Max IOPS: 3499 >>>>> Min IOPS: 0 >>>>> Average Latency(s): 0.0317779 >>>>> Stddev Latency(s): 0.164076 >>>>> Max latency(s): 2.27707 >>>>> Min latency(s): 0.0013848 >>>>> Cleaning up (deleting benchmark objects) >>>>> Clean up completed and total clean up time :20.166559 >>>>> >>>>> >>>>> >>>>> >>>>> On Wed, Oct 18, 2017 at 8:51 AM, Maged Mokhtar >>>>> <mmokh...@petasan.org> >>>>> wrote: >>>>> >>>>> First a general comment: local RAID will be faster than Ceph >>>>> for a >>>>> single threaded (queue depth=1) io operation test. A single >>>>> thread Ceph >>>>> client will see at best same disk speed for reads and for >>>>> writes 4-6 times >>>>> slower than single disk. Not to mention the latency of local >>>>> disks will >>>>> much better. Where Ceph shines is when you have many >>>>> concurrent ios, it >>>>> scales whereas RAID will decrease speed per client as you add >>>>> more. >>>>> >>>>> Having said that, i would recommend running rados/rbd >>>>> bench-write >>>>> and measure 4k iops at 1 and 32 threads to get a better idea >>>>> of how your >>>>> cluster performs: >>>>> >>>>> ceph osd pool create testpool 256 256 >>>>> rados bench -p testpool -b 4096 30 write -t 1 >>>>> rados bench -p testpool -b 4096 30 write -t 32 >>>>> ceph osd pool delete testpool testpool >>>>> --yes-i-really-really-mean-it >>>>> >>>>> rbd bench-write test-image --io-threads=1 --io-size 4096 >>>>> --io-pattern rand --rbd_cache=false >>>>> rbd bench-write test-image --io-threads=32 --io-size 4096 >>>>> --io-pattern rand --rbd_cache=false >>>>> >>>>> I think the request size difference you see is due to the io >>>>> scheduler in the case of local disks having more ios to >>>>> re-group so has a >>>>> better chance in generating larger requests. Depending on >>>>> your kernel, the >>>>> io scheduler may be different for rbd (blq-mq) vs sdx (cfq) >>>>> but again i >>>>> would think the request size is a result not a cause. >>>>> >>>>> Maged >>>>> >>>>> On 2017-10-17 23:12, Russell Glaue wrote: >>>>> >>>>> I am running ceph jewel on 5 nodes with SSD OSDs. >>>>> I have an LVM image on a local RAID of spinning disks. >>>>> I have an RBD image on in a pool of SSD disks. >>>>> Both disks are used to run an almost identical CentOS 7 >>>>> system. >>>>> Both systems were installed with the same kickstart, though >>>>> the disk >>>>> partitioning is different. >>>>> >>>>> I want to make writes on the the ceph image faster. For >>>>> example, >>>>> lots of writes to MySQL (via MySQL replication) on a ceph SSD >>>>> image are >>>>> about 10x slower than on a spindle RAID disk image. The MySQL >>>>> server on >>>>> ceph rbd image has a hard time keeping up in replication. >>>>> >>>>> So I wanted to test writes on these two systems >>>>> I have a 10GB compressed (gzip) file on both servers. >>>>> I simply gunzip the file on both systems, while running >>>>> iostat. >>>>> >>>>> The primary difference I see in the results is the average >>>>> size of >>>>> the request to the disk. >>>>> CentOS7-lvm-raid-sata writes a lot faster to disk, and the >>>>> size of >>>>> the request is about 40x, but the number of writes per second >>>>> is about the >>>>> same >>>>> This makes me want to conclude that the smaller size of the >>>>> request >>>>> for CentOS7-ceph-rbd-ssd system is the cause of it being >>>>> slow. >>>>> >>>>> >>>>> How can I make the size of the request larger for ceph rbd >>>>> images, >>>>> so I can increase the write throughput? >>>>> Would this be related to having jumbo packets enabled in my >>>>> ceph >>>>> storage network? >>>>> >>>>> >>>>> Here is a sample of the results: >>>>> >>>>> [CentOS7-lvm-raid-sata] >>>>> $ gunzip large10gFile.gz & >>>>> $ iostat -x vg_root-lv_var -d 5 -m -N >>>>> Device: rrqm/s wrqm/s r/s w/s rMB/s >>>>> wMB/s >>>>> avgrq-sz avgqu-sz await r_await w_await svctm %util >>>>> ... >>>>> vg_root-lv_var 0.00 0.00 30.60 452.20 13.60 >>>>> 222.15 >>>>> 1000.04 8.69 14.05 0.99 14.93 2.07 100.04 >>>>> vg_root-lv_var 0.00 0.00 88.20 182.00 39.20 >>>>> 89.43 >>>>> 974.95 4.65 9.82 0.99 14.10 3.70 100.00 >>>>> vg_root-lv_var 0.00 0.00 75.45 278.24 33.53 >>>>> 136.70 >>>>> 985.73 4.36 33.26 1.34 41.91 0.59 20.84 >>>>> vg_root-lv_var 0.00 0.00 111.60 181.80 49.60 >>>>> 89.34 >>>>> 969.84 2.60 8.87 0.81 13.81 0.13 3.90 >>>>> vg_root-lv_var 0.00 0.00 68.40 109.60 30.40 >>>>> 53.63 >>>>> 966.87 1.51 8.46 0.84 13.22 0.80 14.16 >>>>> ... >>>>> >>>>> [CentOS7-ceph-rbd-ssd] >>>>> $ gunzip large10gFile.gz & >>>>> $ iostat -x vg_root-lv_data -d 5 -m -N >>>>> Device: rrqm/s wrqm/s r/s w/s rMB/s >>>>> wMB/s >>>>> avgrq-sz avgqu-sz await r_await w_await svctm %util >>>>> ... >>>>> vg_root-lv_data 0.00 0.00 46.40 167.80 0.88 >>>>> 1.46 >>>>> 22.36 1.23 5.66 2.47 6.54 4.52 96.82 >>>>> vg_root-lv_data 0.00 0.00 16.60 55.20 0.36 >>>>> 0.14 >>>>> 14.44 0.99 13.91 9.12 15.36 13.71 98.46 >>>>> vg_root-lv_data 0.00 0.00 69.00 173.80 1.34 >>>>> 1.32 >>>>> 22.48 1.25 5.19 3.77 5.75 3.94 95.68 >>>>> vg_root-lv_data 0.00 0.00 74.40 293.40 1.37 >>>>> 1.47 >>>>> 15.83 1.22 3.31 2.06 3.63 2.54 93.26 >>>>> vg_root-lv_data 0.00 0.00 90.80 359.00 1.96 >>>>> 3.41 >>>>> 24.45 1.63 3.63 1.94 4.05 2.10 94.38 >>>>> ... >>>>> >>>>> [iostat key] >>>>> w/s == The number (after merges) of write requests completed >>>>> per >>>>> second for the device. >>>>> wMB/s == The number of sectors (kilobytes, megabytes) written >>>>> to the >>>>> device per second. >>>>> avgrq-sz == The average size (in kilobytes) of the requests >>>>> that >>>>> were issued to the device. >>>>> avgqu-sz == The average queue length of the requests that >>>>> were >>>>> issued to the device. >>>>> >>>>> >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> 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 >>>>> >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> ceph-users@lists.ceph.com >>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Christian Balzer Network/Systems Engineer >>>>> ch...@gol.com Rakuten Communications >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> 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 >>>>> >>>>> >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> 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 >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> _______________________________________________ >>>> ceph-users mailing list >>>> ceph-users@lists.ceph.com >>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>> >>>> >>> >>> >>> -- >>> Brian Andrus | Cloud Systems Engineer | DreamHost >>> brian.and...@dreamhost.com | www.dreamhost.com >>> >>> >>> >> >> >> -- >> Brian Andrus | Cloud Systems Engineer | DreamHost >> brian.and...@dreamhost.com | www.dreamhost.com >> > >
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