Today a user asked me whether a file on one host can be different on
another host. I was busy composing an answer to tell that the /home
space on all clients are mounted using NFS from the file server. Any
host will therefor see the same file. The user pointed me to his file
and I copied this file from the client and compared this with the file
on the file server. To my surprise it turned out that he was right, the
files were different. I created a new file in this directory and it was
not created on the file server. I renamed the file, and that was only
seen on this single client. How can this happen?
My setup
file server (arend)
CentOS release 4.6
# grep /home /etc/exports
/home *(rw,sync,no_subtree_check)
On the clients (also CentOS release 4.6) I mount /home with these options:
arend:/home /home nfs
proto=tcp,nfsvers=3,bg,defaults 0 0
To debug I created (su stbo) on the client small test files (touch test)
in each directory all the way to the user /home dir. It turns out that
one subdirectory and everything below was not synchronized to the
server. I could create files, move them, but it was just as if I was
working on a local disk. Other users did not experience any problem on
this machine so it was only one sub-directory (and everything below).
I checked the syslog both on the client and on the server, but no
messages of interest.
[root@arend ~]# stat
/home/stbo/workarea/toekan/design/dig/vhdl/fpga/fpga_top.vhd
File: `/home/stbo/workarea/toekan/design/dig/vhdl/fpga/fpga_top.vhd'
Size: 53214 Blocks: 112 IO Block: 4096 regular file
Device: fd01h/64769d Inode: 6614395 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 635/ stbo) Gid: ( 635/ stbo)
Access: 2008-05-14 12:46:34.000000000 +0200
Modify: 2008-05-14 10:08:07.000000000 +0200
Change: 2008-05-14 10:08:07.000000000 +0200
I renamed the filename on the client and did stat there as well. The
modify time shows this file is indeed older as the user mentioned.
[stbo@junco /root]$stat
/home/stbo/workarea/toekan/design/dig/vhdl/fpga/fpga_top.vhd_theo_test
File:
`/home/stbo/workarea/toekan/design/dig/vhdl/fpga/fpga_top.vhd_theo_test'
Size: 53214 Blocks: 112 IO Block: 32768 regular file
Device: 14h/20d Inode: 6583089 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 635/ stbo) Gid: ( 635/ stbo)
Access: 2008-05-14 12:47:07.000000000 +0200
Modify: 2008-04-09 13:09:23.000000000 +0200
Change: 2008-05-14 12:24:24.000000000 +0200
After rebooting everything is normal again:
[root@junco ~]# stat
/home/stbo/workarea/toekan/design/dig/vhdl/fpga/fpga_top.vhd
File: `/home/stbo/workarea/toekan/design/dig/vhdl/fpga/fpga_top.vhd'
Size: 53214 Blocks: 112 IO Block: 32768 regular file
Device: 14h/20d Inode: 6614395 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 635/ stbo) Gid: ( 635/ stbo)
Access: 2008-05-14 12:46:34.000000000 +0200
Modify: 2008-05-14 10:08:07.000000000 +0200
Change: 2008-05-14 10:08:07.000000000 +0200
Any clue what could have gone wrong? Since I trust on a working NFS, I
like to understand what could have gone wrong. Any suggestions are welcome.
Thanks,
Theo
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