defragmentation on fs

[Atil Volkan Yildirim]

hi there,
according to following outputs,can anyone tell me if the fs needs defragmentation???can i really defrag online with onlineJFS,without any problems???and one more question:online or not,how much does it approx. take to defrag a 16 GB data(a 42GB fs standing on a LUN of disk array,16GB being used)...?they say it takes too much?does it???
thx,rgrds...
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fsadm -F vxfs -D /myfs
Directory Fragmentation Report
Dirs searched:372
total blocks: 3532
immed dirs:279
immeds to add:17
dirs to reduce:27
blocks to reduce:3328
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fsadm -F vxfs -E /myfs
Extent Fragmentation Report
Total Average Average Total Files File Blks # Extents Free Blks
7369 2190 2 26692812
blocks used for indirects: 640
% Free blocks in extents smaller than 64 blks: 3.49
% Free blocks in extents smaller than 8 blks: 0.47
% blks allocated to extents 64 blks or larger: 99.27
Free Extents By Size
1: 1124 2: 1092
4: 888 8: 1038
16: 855 32: 693
64: 576 128: 417
256: 355 512: 249
1024: 184 2048: 66
4096: 34 8192: 40
16384: 19 32768: 112

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[Vincenzo Restuccia · Accepted solution]

This gives a report on your fragmentation. To perform the defragmentation you run

# fsadm -F vxfs -d -e -D -E

[James R. Ferguson]

Hi:

A very good discussion of how to evaluate the fragmentation report can be found in the man pages for 'fsadm_vxfs'. In part:

/begin_quote/

To determine whether fragmentation exists for a given file system, the free extents for that file system need to be examined. If a large number small extents are free, then there is fragmentation. If more than half of the amount of free space is taken up by small extents (smaller than 64 blocks), or there is less than 5 percent of total file system space available in large extents, then there is serious fragmentation.

/end_quote/

Your filesystem does not appear to require reorganization.

To limit the time degragmentaton is allowed to run you have the '-t' (time) option and the '-p' (number of passes) option. Again, see the man pages for more details.

...JRF...