On 04/11/2013 07:25 PM, Ziemowit Pierzycki wrote:
No, I'm not using RDMA in this configuration since this will eventually get deployed to production with 10G ethernet (yes RDMA is faster). I would prefer Ceph because it has a storage drive built into OpenNebula which my company is using and as you mentioned individual drives. I'm not sure what the problem is but it appears to me that one of the hosts may be holding up the rest... with Ceph if the performance of one of the hosts is much faster than others could this potentially slow down the cluster to this level?
Definitely! Even 1 slow OSD can cause dramatic slow downs. This is because we (by default) try to distribute data evenly to every OSD in the cluster. If even 1 OSD is really slow, it will accumulate more and more outstanding operations while all of the other OSDs complete their requests. What will happen is that eventually you will have all of your outstanding operations waiting on that slow OSD, and all of the other OSDs will sit idle waiting for new requests.
If you know that some OSDs are permanently slower than others, you can re-weight them so that they receive fewer requests than the others which can mitigate this, but that isn't always an optimal solution. Some times a slow OSD can be a sign of other hardware problems too.
Mark
On Thu, Apr 11, 2013 at 7:42 AM, Mark Nelson <mark.nelson@xxxxxxxxxxx <mailto:mark.nelson@xxxxxxxxxxx>> wrote: With GlusterFS are you using the native RDMA support? Ceph and Gluster tend to prefer pretty different disk setups too. Afaik RH still recommends RAID6 beind each brick while we do better with individual disks behind each OSD. You might want to watch the OSD admin socket and see if operations are backing up on any specific OSDs. Mark On 04/09/2013 12:54 PM, Ziemowit Pierzycki wrote: Neither made a difference. I also have a glusterFS cluster with two nodes in replicating mode residing on 1TB drives: [root@triton speed]# dd conv=fdatasync if=/dev/zero of=/mnt/speed/test.out bs=512k count=10000 10000+0 records in 10000+0 records out 5242880000 bytes (5.2 GB) copied, 43.573 s, 120 MB/s ... and Ceph: [root@triton temp]# dd conv=fdatasync if=/dev/zero of=/mnt/temp/test.out bs=512k count=10000 10000+0 records in 10000+0 records out 5242880000 bytes (5.2 GB) copied, 366.911 s, 14.3 MB/s On Mon, Apr 8, 2013 at 4:29 PM, Mark Nelson <mark.nelson@xxxxxxxxxxx <mailto:mark.nelson@xxxxxxxxxxx> <mailto:mark.nelson@inktank.__com <mailto:mark.nelson@xxxxxxxxxxx>>> wrote: On 04/08/2013 04:12 PM, Ziemowit Pierzycki wrote: There is one SSD in each node. IPoIB performance is about 7 gbps between each host. CephFS is mounted via kernel client. Ceph version is ceph-0.56.3-1. I have a 1GB journal on the same drive as the OSD but on a seperate file system split via LVM. Here is output of another test with fdatasync: [root@triton temp]# dd conv=fdatasync if=/dev/zero of=/mnt/temp/test.out bs=512k count=10000 10000+0 records in 10000+0 records out 5242880000 bytes (5.2 GB) copied, 359.307 s, 14.6 MB/s [root@triton temp]# dd if=/mnt/temp/test.out of=/dev/null bs=512k count=10000 10000+0 records in 10000+0 records out 5242880000 bytes (5.2 GB) copied, 14.0521 s, 373 MB/s Definitely seems off! How many SSDs are involved and how fast are they each? The MTU idea might have merit, but I honestly don't know enough about how well IPoIB handles giant MTUs like that. One thing I have noticed on other IPoIB setups is that TCP autotuning can cause a ton of problems. You may want to try disabling it on all of the hosts involved: echo 0 | tee /proc/sys/net/ipv4/tcp_____moderate_rcvbuf If that doesn't work, maybe try setting MTU to 9000 or 1500 if possible. Mark The network traffic appears to match the transfer speeds shown here too. Writing is very slow. On Mon, Apr 8, 2013 at 3:04 PM, Mark Nelson <mark.nelson@xxxxxxxxxxx <mailto:mark.nelson@xxxxxxxxxxx> <mailto:mark.nelson@inktank.__com <mailto:mark.nelson@xxxxxxxxxxx>> <mailto:mark.nelson@inktank. <mailto:mark.nelson@inktank.>____com <mailto:mark.nelson@inktank.__com <mailto:mark.nelson@xxxxxxxxxxx>>>> wrote: Hi, How many drives? Have you tested your IPoIB performance with iperf? Is this CephFS with the kernel client? What version of Ceph? How are your journals configured? etc. It's tough to make any recommendations without knowing more about what you are doing. Also, please use conv=fdatasync when doing buffered IO writes with dd. Thanks, Mark On 04/08/2013 03:00 PM, Ziemowit Pierzycki wrote: Hi, The first test was writing 500 mb file and was clocked at 1.2 GBps. The second test was writing 5000 mb file at 17 MBps. The third test was reading the file at ~400 MBps. On Mon, Apr 8, 2013 at 2:56 PM, Gregory Farnum <greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx>> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx>>> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx>> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx> <mailto:greg@xxxxxxxxxxx <mailto:greg@xxxxxxxxxxx>>>>> wrote: More details, please. You ran the same test twice and performance went up from 17.5MB/s to 394MB/s? How many drives in each node, and of what kind? -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com On Mon, Apr 8, 2013 at 12:38 PM, Ziemowit Pierzycki <ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx>__> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx>__>__> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx>__> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx> <mailto:ziemowit@xxxxxxxxxxxxx <mailto:ziemowit@xxxxxxxxxxxxx>__>__>__>> wrote: > Hi, > > I have a 3 node SSD-backed cluster connected over infiniband (16K MTU) and > here is the performance I am seeing: > > [root@triton temp]# !dd > dd if=/dev/zero of=/mnt/temp/test.out bs=512k count=1000 > 1000+0 records in > 1000+0 records out > 524288000 bytes (524 MB) copied, 0.436249 s, 1.2 GB/s > [root@triton temp]# dd if=/dev/zero of=/mnt/temp/test.out bs=512k > count=10000 > 10000+0 records in > 10000+0 records out > 5242880000 bytes (5.2 GB) copied, 299.077 s, 17.5 MB/s > [root@triton temp]# dd if=/mnt/temp/test.out of=/dev/null bs=512k > count=1000010000+0 records in > 10000+0 records out > 5242880000 bytes (5.2 GB) copied, 13.3015 s, 394 MB/s > > Does that look right? How do I check this is not a network problem, because > I remember seeing a kernel issue related to large MTU. > > _____________________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>> <mailto:ceph-users@xxxxxxxxxx. <mailto:ceph-users@xxxxxxxxxx.>____com <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>>> <mailto:ceph-users@xxxxxxxxxx <mailto:ceph-users@xxxxxxxxxx>. <mailto:ceph-users@xxxxxxxxxx <mailto:ceph-users@xxxxxxxxxx>.__>____com <mailto:ceph-users@xxxxxxxxxx. <mailto:ceph-users@xxxxxxxxxx.>____com <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>>>> > http://lists.ceph.com/______listinfo.cgi/ceph-users-ceph.______com <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com> <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com>> <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com> <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com <http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com>>> > _____________________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>> <mailto:ceph-users@xxxxxxxxxx. <mailto:ceph-users@xxxxxxxxxx.>____com <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>>> http://lists.ceph.com/______listinfo.cgi/ceph-users-ceph.______com <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com> <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com>> <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com> <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com <http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com>>> _____________________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>> <mailto:ceph-users@xxxxxxxxxx. <mailto:ceph-users@xxxxxxxxxx.>____com <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>>> http://lists.ceph.com/______listinfo.cgi/ceph-users-ceph.______com <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com> <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com>> <http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com> <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com <http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com>>> ___________________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>> http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com> <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com <http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com>> ___________________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> <mailto:ceph-users@xxxxxxxxxx.__com <mailto:ceph-users@xxxxxxxxxxxxxx>> http://lists.ceph.com/____listinfo.cgi/ceph-users-ceph.____com <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com> <http://lists.ceph.com/__listinfo.cgi/ceph-users-ceph.__com <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
