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-ima >>> 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
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