General FS questions

[ShazMagwar]

Good day.
I've got some basic questions about Filesytems...any tips appreciated

1) Fragmentation ==>

• I'm under the impression that there's no defrag'ing ext3. Is this correct?
• If not, that seems...kinda weird. Is it good enough to not "need" one?
• Which FS's have defrag utils?

2) Picking one ==>

• Is there any suggestions about which FS is better suited for certain tasks for Desktop/Workstation usage (ie should I use ext3 for system partition, XXX for everyday data, YYY for multimedia partition (large video files))
• Keep in mind that I'm not running some huge compile farm. It's a small SOHO network. I'm a Linux newcomer but I'm trying to homogenize my personal computing with my engineering/math work.

3) Windows ==> I need a drive that both Linux & WinXP can R/W to. Do I need to go FAT?

thanks
~S

[mlau]

1.) I'm no expert on that, however the general opinion on
linux-fs-devel is that ext2/3 don't fragment files as bad as
fat/ntfs do (they leave larger gaps between files, etc).
Namesys (the makers of reiserfs/reiser4) have indicated a few
times that they'd write a repacker if someone paid them to do
so. So essentially none of the popular linux fs have defrag
utils right now (and don't really need them)

2.)
For standard desktop tasks any journalling fs will do
(ext3, reiser3/4, xfs). You can tell ext2/3 at creation time
what you intend to use the fs for (large or small files, frequent deletes/creations, etc,) and it will optimize the
disk layout a bit.

XFS is king when you need to read/write multiple video streams
to/from disks with guaranteed bandwidths (after all, thats
what it was designed for in the IRIX days...)

Reiser4 comes with a compression plugin which does file
compression on the fly; in theory you could achieve read speeds
in excess of the max disk read speeds, however when a block
on the disk goes bad you're royally screwed

(My main gateway machine runs reiser3; it has survived ~200
power outages without ever losing a file. This machine also
runs a mailserver which stores ~4k mails/week. However it feels
slower than other fs)

3.) Check out http://www.ifs-driver.org It's an Ext2 driver
for windows NT line, in essence it allows you to give out
disk letters to ext2/3 filesystems. I use it on a number of
machines and I love it: You can read/write files on both win
and linux (like FAT32) but without the file/volumesize limits
imposed by FAT.

[glussier]

With the use of ntfs-3g you can have ntfs read/write access from linux.

[ShazMagwar]

thanks people.

funny enough I was going through some older mags I hadn't quite finished reading
& came across ntfsprogs and that ntfs-3g driver ...it all seems pretty comprehensive

Reiser sounds good
...though on-the-fly compression (on any FS) has always been a bit scary

[deanjo]

Actually XFS does have a defragger. It does come in handy when doing things such as bittorrent when the client does not preallocate space.

Say my /home directory was mounted /dev/hda1 and we wanted to check the amount of fragmentation it had. What we need here is the package called xfsdump. Check your distro's instructions as to how to install it if you don't already have it.

Now to check the degree of fragmentation we issue this command as super user.

Code:
xfs_db -r /dev/hda1
xfs_db> frag


it should come back (length of time depends on level of fragmentation) giving you a analysis of the degree of fragmentation such as:

Code:
actual 300086, ideal 299315, fragmentation factor 0.26%


To quit the xfs_db prompt simply type:

Code:
xfs_db> quit



Now to defrag the volume all you have to do is type as super user is:

Code:
xfs_fsr -v /dev/hda1


After a few minutes (again depending on the level of fragmentation) your volume will be defragmented.