Re: Disk defragmenter in Linux

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Jim Cornette wrote:
John Summerfied wrote:

Jeff Vian wrote:


Exactly, and IIRC the filesystem knows that if it needs X amount of
space for a file, then Y number of inodes are marked for use for that
file at the beginning.  Thus space allocated is as contiguous as is
efficient for read/write on the disk.



If "the filesystem knows that if it needs X amount of space for a file," that implies there's a way of telling it that.

How's that done? I don't recall any system call for *x (there is one for OS/2), and one could do it in JCL in IBM's OS in the 60s), but in the *x world I've never seen a way to do it.



Since the discussions regarding fragmentation on ext3 filesystems was pretty long running. I decided to try
filefrag /usr/bin/* |sort |grep 'would be'
and the output showed a lot of fragmentation. One of the files was up to 45.
/usr/bin/postgres: 45 extents found, perfection would be 1 extent
I outputted the findings to a file which ended up being around 75 kb
The log files didn't seems to be as fragmented as I expected. Another pecularity was that some of the files did not seem to be things that I use much.
Another excerpt from the query.
/usr/bin/php: 52 extents found, perfection would be 1 extent
/usr/bin/php-cgi: 62 extents found, perfection would be 1 extent

My system is running development. This of course means frequently updated programs. Checking usr/lib showed fragmentation also.
/usr/lib/libXm.so.4: 48 extents found, perfection would be 1 extent
/usr/lib/libXm.so.4.0.0: 48 extents found, perfection would be 1 extent
..
/usr/lib/libxvidcore.so.4: 49 extents found, perfection would be 1 extent

I guess fragmentation is present on the system and probably needs addressed or a less fragmented filesystem type needs implemented.

extent ^= fragmentation. On filesystems I know, extents can be on consecutive areas (sectors, blocks, tracks) of disk. You need better info than that to see whether you have a fragmentation problem. filefrag will give it to you, but it needs a wrapper to make sense to Mere Mortals.


fwiw
summer@bilby ~]$ sudo filefrag /usr/sbin/postfix /usr/X11R6/lib/libXm*
/usr/sbin/postfix: 1 extent found
/usr/X11R6/lib/libXm.a: 1 extent found
/usr/X11R6/lib/libXm.so: 1 extent found
/usr/X11R6/lib/libXm.so.2: 1 extent found
/usr/X11R6/lib/libXm.so.2.1: 1 extent found
/usr/X11R6/lib/libXm.so.3: 1 extent found
/usr/X11R6/lib/libXm.so.3.0.2: 1 extent found
/usr/X11R6/lib/libXmu.a: 1 extent found
/usr/X11R6/lib/libXmu.so: 2 extents found, perfection would be 1 extent
/usr/X11R6/lib/libXmu.so.6: 2 extents found, perfection would be 1 extent
/usr/X11R6/lib/libXmu.so.6.2: 2 extents found, perfection would be 1 extent
/usr/X11R6/lib/libXmuu.a: 1 extent found
/usr/X11R6/lib/libXmuu.so: 1 extent found
/usr/X11R6/lib/libXmuu.so.1: 1 extent found
/usr/X11R6/lib/libXmuu.so.1.0: 1 extent found

This system was installed as Fedora Core 3, and all these package subsequently replaced (with force where necessary) with packages I built myself from RHEL 4 source. That is, they have all been updated after installation.

Checking lib and bin directories under /usr, I see no more than three extents.

I note my file placement's different from yours.


--

Cheers
John

-- spambait
1aaaaaaa@xxxxxxxxxxxxxxxxxxxxxxx  Z1aaaaaaa@xxxxxxxxxxxxxxxxxxxxxxx
Tourist pics http://portgeographe.environmentaldisasters.cds.merseine.nu/

do not reply off-list


[Index of Archives]     [Current Fedora Users]     [Fedora Desktop]     [Fedora SELinux]     [Yosemite News]     [Yosemite Photos]     [KDE Users]     [Fedora Tools]     [Fedora Docs]

  Powered by Linux