Rama, Thanks for your reply. My end goal is to use iSCSI (with LIO/targetcli) to export rbd block devices. I was encountering issues with iSCSI which are explained in my previous emails. I ended up being able to reproduce the problem at will on various Kernel and OS combinations, even on raw RBD devices - thus ruling out the hypothesis that it was a problem with iSCSI but rather with Ceph. I'm even running 0.88 now and the issue is still there. I haven't isolated the issue just yet. My next tests involve disabling the cache tiering. I do have client krbd cache as well, i'll try to disable it too if cache tiering isn't enough. -- David Moreau Simard > On Nov 18, 2014, at 8:10 PM, Ramakrishna Nishtala (rnishtal) <rnishtal@xxxxxxxxx> wrote: > > Hi Dave > Did you say iscsi only? The tracker issue does not say though. > I am on giant, with both client and ceph on RHEL 7 and seems to work ok, unless I am missing something here. RBD on baremetal with kmod-rbd and caching disabled. > > [root@compute4 ~]# time fio --name=writefile --size=100G --filesize=100G --filename=/dev/rbd0 --bs=1M --nrfiles=1 --direct=1 --sync=0 --randrepeat=0 --rw=write --refill_buffers --end_fsync=1 --iodepth=200 --ioengine=libaio > writefile: (g=0): rw=write, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=200 > fio-2.1.11 > Starting 1 process > Jobs: 1 (f=1): [W(1)] [100.0% done] [0KB/853.0MB/0KB /s] [0/853/0 iops] [eta 00m:00s] > ... > Disk stats (read/write): > rbd0: ios=184/204800, merge=0/0, ticks=70/16164931, in_queue=16164942, util=99.98% > > real 1m56.175s > user 0m18.115s > sys 0m10.430s > > Regards, > > Rama > > > -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of David Moreau Simard > Sent: Tuesday, November 18, 2014 3:49 PM > To: Nick Fisk > Cc: ceph-users@xxxxxxxxxxxxxx > Subject: Re: Poor RBD performance as LIO iSCSI target > > Testing without the cache tiering is the next test I want to do when I have time.. > > When it's hanging, there is no activity at all on the cluster. > Nothing in "ceph -w", nothing in "ceph osd pool stats". > > I'll provide an update when I have a chance to test without tiering. > -- > David Moreau Simard > > > > On Nov 18, 2014, at 3:28 PM, Nick Fisk <nick@xxxxxxxxxx> wrote: > > > > Hi David, > > > > Have you tried on a normal replicated pool with no cache? I've seen a > > number of threads recently where caching is causing various things to block/hang. > > It would be interesting to see if this still happens without the > > caching layer, at least it would rule it out. > > > > Also is there any sign that as the test passes ~50GB that the cache > > might start flushing to the backing pool causing slow performance? > > > > I am planning a deployment very similar to yours so I am following > > this with great interest. I'm hoping to build a single node test > > "cluster" shortly, so I might be in a position to work with you on > > this issue and hopefully get it resolved. > > > > Nick > > > > -----Original Message----- > > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf > > Of David Moreau Simard > > Sent: 18 November 2014 19:58 > > To: Mike Christie > > Cc: ceph-users@xxxxxxxxxxxxxx; Christopher Spearman > > Subject: Re: Poor RBD performance as LIO iSCSI target > > > > Thanks guys. I looked at http://tracker.ceph.com/issues/8818 and > > chatted with "dis" on #ceph-devel. > > > > I ran a LOT of tests on a LOT of comabination of kernels (sometimes > > with tunables legacy). I haven't found a magical combination in which > > the following test does not hang: > > fio --name=writefile --size=100G --filesize=100G --filename=/dev/rbd0 > > --bs=1M --nrfiles=1 --direct=1 --sync=0 --randrepeat=0 --rw=write > > --refill_buffers --end_fsync=1 --iodepth=200 --ioengine=libaio > > > > Either directly on a mapped rbd device, on a mounted filesystem (over > > rbd), exported through iSCSI.. nothing. > > I guess that rules out a potential issue with iSCSI overhead. > > > > Now, something I noticed out of pure luck is that I am unable to > > reproduce the issue if I drop the size of the test to 50GB. Tests will > > complete in under 2 minutes. > > 75GB will hang right at the end and take more than 10 minutes. > > > > TL;DR of tests: > > - 3x fio --name=writefile --size=50G --filesize=50G > > --filename=/dev/rbd0 --bs=1M --nrfiles=1 --direct=1 --sync=0 > > --randrepeat=0 --rw=write --refill_buffers --end_fsync=1 --iodepth=200 > > --ioengine=libaio > > -- 1m44s, 1m49s, 1m40s > > > > - 3x fio --name=writefile --size=75G --filesize=75G > > --filename=/dev/rbd0 --bs=1M --nrfiles=1 --direct=1 --sync=0 > > --randrepeat=0 --rw=write --refill_buffers --end_fsync=1 --iodepth=200 > > --ioengine=libaio > > -- 10m12s, 10m11s, 10m13s > > > > Details of tests here: http://pastebin.com/raw.php?i=3v9wMtYP > > > > Does that ring you guys a bell ? > > > > -- > > David Moreau Simard > > > > > >> On Nov 13, 2014, at 3:31 PM, Mike Christie <mchristi@xxxxxxxxxx> wrote: > >> > >> On 11/13/2014 10:17 AM, David Moreau Simard wrote: > >>> Running into weird issues here as well in a test environment. I > >>> don't > > have a solution either but perhaps we can find some things in common.. > >>> > >>> Setup in a nutshell: > >>> - Ceph cluster: Ubuntu 14.04, Kernel 3.16.7, Ceph 0.87-1 (OSDs with > >>> separate public/cluster network in 10 Gbps) > >>> - iSCSI Proxy node (targetcli/LIO): Ubuntu 14.04, Kernel 3.16.7, > >>> Ceph > >>> 0.87-1 (10 Gbps) > >>> - Client node: Ubuntu 12.04, Kernel 3.11 (10 Gbps) > >>> > >>> Relevant cluster config: Writeback cache tiering with NVME PCI-E > >>> cards (2 > > replica) in front of a erasure coded pool (k=3,m=2) backed by spindles. > >>> > >>> I'm following the instructions here: > >>> http://www.hastexo.com/resources/hints-and-kinks/turning-ceph-rbd-im > >>> a ges-san-storage-devices No issues with creating and mapping a > >>> 100GB RBD image and then creating the target. > >>> > >>> I'm interested in finding out the overhead/performance impact of > > re-exporting through iSCSI so the idea is to run benchmarks. > >>> Here's a fio test I'm trying to run on the client node on the > >>> mounted > > iscsi device: > >>> fio --name=writefile --size=100G --filesize=100G --filename=/dev/sdu > >>> --bs=1M --nrfiles=1 --direct=1 --sync=0 --randrepeat=0 --rw=write > >>> --refill_buffers --end_fsync=1 --iodepth=200 --ioengine=libaio > >>> > >>> The benchmark will eventually hang towards the end of the test for > >>> some > > long seconds before completing. > >>> On the proxy node, the kernel complains with iscsi portal login > >>> timeout: http://pastebin.com/Q49UnTPr and I also see irqbalance > >>> errors in syslog: http://pastebin.com/AiRTWDwR > >>> > >> > >> You are hitting a different issue. German Anders is most likely > >> correct and you hit the rbd hang. That then caused the iscsi/scsi > >> command to timeout which caused the scsi error handler to run. In > >> your logs we see the LIO error handler has received a task abort from > >> the initiator and that timed out which caused the escalation (iscsi > >> portal login related messages). > > > > _______________________________________________ > > 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
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