Hi Josh, Thanks for the information. I am trying to add the following but hitting some permission issue. root@emsclient:/etc# echo <mon-1>:6789,<mon-2>:6789,<mon-3>:6789 name=admin,key=client.admin,noshare test_rbd ceph_block_test' > /sys/bus/rbd/add -bash: echo: write error: Operation not permitted Here is the contents of rbd directory.. root@emsclient:/sys/bus/rbd# ll total 0 drwxr-xr-x 4 root root 0 Sep 19 11:59 ./ drwxr-xr-x 30 root root 0 Sep 13 11:41 ../ --w------- 1 root root 4096 Sep 19 11:59 add drwxr-xr-x 2 root root 0 Sep 19 12:03 devices/ drwxr-xr-x 2 root root 0 Sep 19 12:03 drivers/ -rw-r--r-- 1 root root 4096 Sep 19 12:03 drivers_autoprobe --w------- 1 root root 4096 Sep 19 12:03 drivers_probe --w------- 1 root root 4096 Sep 19 12:03 remove --w------- 1 root root 4096 Sep 19 11:59 uevent I checked even if I am logged in as root , I can't write anything on /sys. Here is the Ubuntu version I am using.. root@emsclient:/etc# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 13.04 Release: 13.04 Codename: raring Here is the mount information.... root@emsclient:/etc# mount /dev/mapper/emsclient--vg-root on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/cgroup type tmpfs (rw) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755) /dev/sda1 on /boot type ext2 (rw) /dev/mapper/emsclient--vg-home on /home type ext4 (rw) Any idea what went wrong here ? Thanks & Regards Somnath -----Original Message----- From: Josh Durgin [mailto:josh.durgin@xxxxxxxxxxx] Sent: Wednesday, September 18, 2013 6:10 PM To: Somnath Roy Cc: Sage Weil; ceph-devel@xxxxxxxxxxxxxxx; Anirban Ray; ceph-users@xxxxxxxxxxxxxx Subject: Re: Scaling RBD module On 09/17/2013 03:30 PM, Somnath Roy wrote: > Hi, > I am running Ceph on a 3 node cluster and each of my server node is running 10 OSDs, one for each disk. I have one admin node and all the nodes are connected with 2 X 10G network. One network is for cluster and other one configured as public network. > > Here is the status of my cluster. > > ~/fio_test# ceph -s > > cluster b2e0b4db-6342-490e-9c28-0aadf0188023 > health HEALTH_WARN clock skew detected on mon. <server-name-2>, mon. <server-name-3> > monmap e1: 3 mons at {<server-name-1>=xxx.xxx.xxx.xxx:6789/0, <server-name-2>=xxx.xxx.xxx.xxx:6789/0, <server-name-3>=xxx.xxx.xxx.xxx:6789/0}, election epoch 64, quorum 0,1,2 <server-name-1>,<server-name-2>,<server-name-3> > osdmap e391: 30 osds: 30 up, 30 in > pgmap v5202: 30912 pgs: 30912 active+clean; 8494 MB data, 27912 MB used, 11145 GB / 11172 GB avail > mdsmap e1: 0/0/1 up > > > I started with rados bench command to benchmark the read performance of this Cluster on a large pool (~10K PGs) and found that each rados client has a limitation. Each client can only drive up to a certain mark. Each server node cpu utilization shows it is around 85-90% idle and the admin node (from where rados client is running) is around ~80-85% idle. I am trying with 4K object size. Note that rados bench with 4k objects is different from rbd with 4k-sized I/Os - rados bench sends each request to a new object, while rbd objects are 4M by default. > Now, I started running more clients on the admin node and the performance is scaling till it hits the client cpu limit. Server still has the cpu of 30-35% idle. With small object size I must say that the ceph per osd cpu utilization is not promising! > > After this, I started testing the rados block interface with kernel rbd module from my admin node. > I have created 8 images mapped on the pool having around 10K PGs and I am not able to scale up the performance by running fio (either by creating a software raid or running on individual /dev/rbd* instances). For example, running multiple fio instances (one in /dev/rbd1 and the other in /dev/rbd2) the performance I am getting is half of what I am getting if running one instance. Here is my fio job script. > > [random-reads] > ioengine=libaio > iodepth=32 > filename=/dev/rbd1 > rw=randread > bs=4k > direct=1 > size=2G > numjobs=64 > > Let me know if I am following the proper procedure or not. > > But, If my understanding is correct, kernel rbd module is acting as a client to the cluster and in one admin node I can run only one of such kernel instance. > If so, I am then limited to the client bottleneck that I stated earlier. The cpu utilization of the server side is around 85-90% idle, so, it is clear that client is not driving. > > My question is, is there any way to hit the cluster with more client from a single box while testing the rbd module ? You can run multiple librbd instances easily (for example with multiple runs of the rbd bench-write command). The kernel rbd driver uses the same rados client instance for multiple block devices by default. There's an option (noshare) to use a new rados client instance for a newly mapped device, but it's not exposed by the rbd cli. You need to use the sysfs interface that 'rbd map' uses instead. Once you've used rbd map once on a machine, the kernel will already have the auth key stored, and you can use: echo '1.2.3.4:6789 name=admin,key=client.admin,noshare poolname imagename' > /sys/bus/rbd/add Where 1.2.3.4:6789 is the address of a monitor, and you're connecting as client.admin. You can use 'rbd unmap' as usual. Josh ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. 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