On Fri, Feb 27, 2009 at 12:31 AM, Andrzej Szymański <szym...@agh.edu.pl> wrote: > Hello, > > Does anybody know how to avoid the file fragmentation when a file is > created over NFSv3? > > A file created locally is OK: > dd bs=32k if=/dev/zero of=test count=32x1024 conv=fsync > filefrag test > test: 10 extents found, perfection would be 9 extents > > When I create the file in the same dir, but from another machine, > mounted over NFS: > > filefrag test > test: 4833 extents found, perfection would be 9 extents
1) what is filefrag and where is it from? 2) Have you played with adding/subtracting threads to see if that helps? 3) What happens if you don't use fsync on the dd. 4) What happens if you use larger/smaller bs 5) Is the rsize/wsize onthe server 32768 or some other number. I thought the default w/size on an export was 512 or some small number. > With such a file a sequential read is quite slow (~76MB vs >200MB on my > raid card). > > I can just suspect that this is a problem of block allocation when the > same file is appended by different processes (8 NFS threads). > > I've tried mounting ext3 with -o reservation and switch to NFS over TCP, > with no improvement. > > Both systems are Centos 5.2 with kernel 2.6.18-92.1.22.el5 > The ext3 is mounted with rw,nosuid,nodev,usrquota,grpquota,acl > NFS export: rw,sync,no_root_squash > 8 NFS threads. > Remotely mounted with options > rw,intr,nfsvers=3,proto=udp,rsize=32768,wsize=32768 > > I would be very grateful for any help. > > Andrzej > _______________________________________________ > CentOS mailing list > CentOS@centos.org > http://lists.centos.org/mailman/listinfo/centos > -- Stephen J Smoogen. -- BSD/GNU/Linux How far that little candle throws his beams! So shines a good deed in a naughty world. = Shakespeare. "The Merchant of Venice" _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
