On 06/05/12 09:26, Daniel Pocock wrote: > > > I've been observing some very slow nfs write performance when the server > has `sync' in /etc/exports > > I want to avoid using async, but I have tested it and on my gigabit > network, it gives almost the same speed as if I was on the server > itself. (e.g. 30MB/sec to one disk, or less than 1MB/sec to the same > disk over NFS with `sync') Just to clarify this point: if I log in to the server and run one of my tests (e.g. untar the linux source), it is very fast, iostat shows 30MB/sec write) Also, I've tried write-back cache (hdparm -W 1), when this is enabled NFS writes go from about 1MB/sec up to about 10MB/sec, but still way below the speed of local disk access on the server. > > I'm using Debian 6 with 2.6.38 kernels on client and server, NFSv3 > > I've also tried a client running Debian 7/Linux 3.2.0 with both NFSv3 > and NFSv4, speed is still slow > > Looking at iostat on the server, I notice that avgrq-sz = 8 sectors > (4096 bytes) throughout the write operations > > I've tried various tests, e.g. dd a large file, or unpack a tarball with > many small files, the iostat output is always the same > > Looking at /proc/mounts on the clients, everything looks good, large > wsize, tcp: > > rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.x.x.x,mountvers=3,mountport=58727,mountproto=udp,local_lock=none,addr=192.x.x.x > 0 0 > > and > rw,relatime,vers=4,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.x.x.x.,minorversion=0,local_lock=none,addr=192.x.x.x 0 0 > > and in /proc/fs/nfs/exports on the server, I have sync and wdelay: > > /nfs4/daniel > 192.168.1.0/24,192.x.x.x(rw,insecure,root_squash,sync,wdelay,no_subtree_check,uuid=aa2a6f37:9cc94eeb:bcbf983c:d6e041d9,sec=1) > /home/daniel > 192.168.1.0/24,192.x.x.x(rw,root_squash,sync,wdelay,no_subtree_check,uuid=aa2a6f37:9cc94eeb:bcbf983c:d6e041d9) > > Can anyone suggest anything else? Or is this really the performance hit > of `sync'? > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
