[CentOS] centos 6.2 xfs + nfs space allocation

Stephan van Hienen

ddx at a2000.nu
Mon Jun 11 09:27:54 UTC 2012


Centos 6.2 system with xfs filesystem.
I'm sharing this filesystem using nfs.

When I create a 10 gigabyte test file from a nfs client system :

dd if=/dev/zero of=10Gtest bs=1M count=10000
10000+0 records in
10000+0 records out
10485760000 bytes (10 GB) copied, 74.827 s, 140 MB/s

Output from 'ls -al ; du' during this test :

-rw-r--r-- 1 root root 429170688 Jun  8 10:13 10Gtest
654456  10Gtest

-rw-r--r-- 1 root root 1756831744 Jun  8 10:13 10Gtest
2230720 10Gtest

-rw-r--r--   1 root root 2492145664 Jun  8 10:11 10Gtest
4348288 10Gtest

-rw-r--r--   1 root root 4686782464 Jun  8 10:11 10Gtest
8542592 10Gtest

-rw-r--r-- 1 root root 10485760000 Jun  8 10:12 10Gtest
16943552        10Gtest

The file is using almost double the size ?
Even after a few days the file is showing the same disk usage.
Only umounting and remounting the filesystem fixes the problem.
When I do the same test on an ext4 filesystem no issues. (same 
server/client)

Same issue on 2 centos 6.2 servers.
I also tried to reproduce the issue on an rhel 5.8 system with xfs, but 
here the disk usage is ok.
(I don't have a rhel6 systems with the xfs addon subscription)

Stephan



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