On 4/4/07, <b class="gmail_sendername">catfish</b> <<a href="mailto:catfish@halfdone.com">catfish@halfdone.com</a>> wrote:<div><span class="gmail_quote"></span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Michael MacLeod wrote:<br>> root@sixball:~# xfs_db -r /dev/mythtv/mythmedia<br>> xfs_db> frag<br>> actual 3904, ideal 3191, fragmentation factor 18.26%<br>> xfs_db> quit<br>><br>> I just thought I'd share this with the list, and ask if anyone else has
<br>> encountered significant performance loss due to disk fragmentation? How<br>> fragmented are your drives?<br><br>Robert wrote:<br>> mythbox ~ # xfs_db -r /dev/mapper/vg-mythtv<br>> xfs_db> frag<br>> actual 60667, ideal 67, fragmentation factor
99.89%<br>> xfs_db><br>><br>> Hmm, that looks pretty bad.<br><br><br>Very interesting, think it would effect JFS also? I can't seem to locate<br>an equivalent tool for it.<br><br></blockquote></div><br>On my 'Jarod Wilson' Fedora box which uses Jfs I can use filefrag:
<br>
<br>
[root@mythtv video]# filefrag -v /video/9_20060901222500_20060902011000.nuv<br>
Checking /video/9_20060901222500_20060902011000.nuv<br>
Filesystem type is: 3153464a<br>
Filesystem cylinder groups is approximately 89128<br>
Blocksize of file /video/9_20060901222500_20060902011000.nuv is 4096<br>
File size of /video/9_20060901222500_20060902011000.nuv is 7249782490 (1769967 blocks)<br>
First block: 23647088<br>
Last block: 25417064<br>
Discontinuity: Block 761811 is at 24408904 (was 24408898)<br>
Discontinuity: Block 1518731 is at 25165825 (was 25165823)<br>
Discontinuity: Block 1518734 is at 25165832 (was 25165827)<br>
/video/9_20060901222500_20060902011000.nuv: 4 extents found<br>
<br>
I interpret this info as 4 continuus blocks for a 7GB file which seems good. I
tested a few other files and all had a small amount of extents. The
system is now running about 16 months and I did not take any
defragmentation actions. I regularly record two shows at a time with a PVR500 and I see no weird values.<br>
<br>
You can also test multiple files like:<br>
<br>
[root@mythtv video]# filefrag /video/*<br>
/video/1001_20070403041300.mpg: 5 extents found<br>
/video/1001_20070403041300.mpg.png: 1 extent found<br>
/video/1011_20070401152300.mpg: 3 extents found<br>
/video/1011_20070401152300.mpg.png: 1 extent found<br>
/video/1069_20061111231036.mpg: 1 extent found<br>
/video/1069_20061111231036.mpg.png: 1 extent found<br>
/video/1070_20061111231041.mpg: 1 extent found<br>
/video/1070_20061111231041.mpg.png: 1 extent found<br>
..<br>
..<br>
<br>
or with the -v option to get more info<br>
<br>
One program I could find is Fibmap from some research done about the
fragmentation in different filesystems, the site seems to be updated in
2004 for the last time....<br>
<a href="http://www.informatik.uni-frankfurt.de/~loizides/reiserfs/fibmap.html#description">http://www.informatik.uni-frankfurt.de/~loizides/reiserfs/fibmap.html#description</a><br>
I did not test the program.<br>
<br>
Martijn<br>