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
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
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