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