Trouble Interpreting Fragmentation Reports

[Tim_Rainier]

I am having some trouble trying to understand the output from the 'fsadm -E /mount-point' command. Take a filesystem like /rlog01. It's oracle tablespace, vxfs, 10g used out of 20g, and comprised of only 15 files, relatively large in size (~300MB). The output of 'fsadm -E /rlog01' is:

# fsadm -E /rlog01
Extent Fragmentation Report
Total Average Average Total
Files File Blks # Extents Free Blks
17 76908 210 2585124
blocks used for indirects: 13
% Free blocks in extents smaller than 64 blks: 0.01
% Free blocks in extents smaller than 8 blks: 0.00
% blks allocated to extents 64 blks or larger: 99.99
Free Extents By Size
1: 6 2: 5 4: 5
8: 0 16: 2 32: 3
64: 2 128: 2 256: 2
512: 3 1024: 4 2048: 1
4096: 3 8192: 3 16384: 3
32768: 2 65536: 1 131072: 0
262144: 1 524288: 0 1048576: 2
2097152: 0 4194304: 0 8388608: 0
16777216: 0 33554432: 0 67108864: 0
134217728: 0 268435456: 0 536870912: 0
1073741824: 0 2147483648: 0

Does anyone care to help me understand? At first-glance it looks to be terribly fragmented.

[Carsten_Hennig]

Hi Tim,

this looks perfect. For the three lines beginning with "%", the number should be <1, <1, >80, which you perfectly hit. The larger the free extents are, the better. And the used space should be allocated to extents larger 64 blocks. Your file system met all the critical criteria.
This is not fragmented.

Regards,
Carsten

[Tim_Rainier]

Does the size or average size of files on the filesystem change that criteria?

[Carsten_Hennig]

No, this is a general rule of thumb.

-CH

[Tim_Rainier]

Great. Thanks a bunch.