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Reiserfs

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I've been reading on the Gentoo Forums about Reiser. There's a lot of contention that it's a bad file system because it fragments quickly. The only thing I've read that you can do is add noatime to /etc/fstab and periodically move everything to a spare partition and reformat. They say there is no way to check reiser for fragmentation. They are saying that the initial speed you get from using reiser is quickly lost because of fragmentation. I've been using reiser for years and never noticed this and never had a problem. Thoughts?

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I have no opinion :)

/dev/hda3 on / type reiserfs (rw,noatime)
/dev/hda5 on /home type reiserfs (rw,noatime)
/dev/hda6 on /var type reiserfs (rw,noatime)
/dev/hda7 on /var/log type reiserfs (rw,noatime)
/dev/hda8 on /tmp type reiserfs (rw,noatime)
/dev/hda9 on /usr/portage type reiserfs (rw,noatime)
/dev/hda10 on /www type reiserfs (rw,noatime)
/dev/hda11 on /mail type reiserfs (rw,noatime)
/dev/hda12 on /backup type reiserfs (rw,noatime)
/dev/hdc1 on /seraph type reiserfs (rw,noatime)
/dev/hdd1 on /mandrivauser type reiserfs (rw,noatime)

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I used it for 2 years without any problems, and never noticed any speed issues either. What are they smoking?

I use ext3 now though, simply because I use PM8 for partition management and bkup.

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I have used Reiser and ext3 both never any issues. I have heard this about reiser before, but have never seen it happen. Of course I have also used reiser in situations that I was told wouldn't work, and had no difficulties. I guess I just don't listen! :jester:

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i think it's just another one of those useless geek arguments...like i said on IRC. whether or not there's truth to it isn't my concern, as I've had no perfomance issues. Plus, there are a good few tests of the various filesystems out there to help you pick the best one for your need :)

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I only know that reiserfs has some problems with hard-locking system files (that's why I use ext3 there), but on my /home partitions it never slowed down. I guess it is one of those weird rumours that emerge from time to time.

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Rebuilt my system the other day mirroring / and all my partitions are reiserfs:

 

fdisk -l /dev/hda

Disk /dev/hda: 20.0 GB, 20020396032 bytes
255 heads, 63 sectors/track, 2434 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1          12       96358+  83  Linux
/dev/hda2              13        2434    19454715   fd  Linux raid autodetect
[root@esprit ian]# fdisk -l /dev/hdb

Disk /dev/hdb: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start         End      Blocks   Id  System
/dev/hdb1   *           1         125     1004031   82  Linux swap / Solaris
/dev/hdb2             126        2547    19454715   fd  Linux raid autodetect
/dev/hdb3            2548       19457   135829575    5  Extended
/dev/hdb5            2548       19457   135829543+  83  Linux

 

incidently, prior to this I was using xfs, and I was noticing weird problems, and my file systems were getting real screwed up. Even the partition tables were reporting problems when I listed using fdisk -l. Bizarre, not sure what happened, but it seems so much better now.

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Well, some guy on the Gentoo Forums wrote a perl script to detect fragmentation. This is what I got.

gentoo scripts # ./frag.pl /
1.84820798861254% non contiguous files, 1.04510542095924 average fragments.
gentoo scripts # ./frag.pl /home
0.988932063866227% non contiguous files, 2.90432957035782 average fragments.

 

The / partition was reformatted about two months ago when I reinstalled.

/home is about 2 1/2 years old.

 

If anybody wants the script let me know.

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Cool, yeah, I'd love the script, just to run and check it out.

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You have to run chmod u+x on the script and save it with a .pl extention, then run it using ./

 

#!/usr/bin/perl -w 

#this script search for frag on a fs 
use strict; 

#number of files 
my $files = 0; 
#number of fragment 
my $fragments = 0; 
#number of fragmented files 
my $fragfiles = 0; 

#search fs for all file 
open (FILES, "find " . $ARGV[0] . " -xdev -type f |"); 

while (defined (my $file = <FILES>)) { 
       #quote some chars in filename 
       $file =~ s/!/\\!/g; 
       $file =~ s/#/\\#/g; 
       $file =~ s/&/\\&/g; 
       $file =~ s/>/\\>/g; 
       $file =~ s/</\\</g; 
       $file =~ s/\$/\\\$/g; 
       $file =~ s/\(/\\\(/g; 
       $file =~ s/\)/\\\)/g; 
       $file =~ s/\|/\\\|/g; 
       $file =~ s/'/\\'/g; 
       $file =~ s/ /\\ /g; 
       #nb of fragment for the file 
       open (FRAG, "filefrag $file |"); 
       my $res = <FRAG>; 
       if ($res =~ m/.*:\s+(\d+) extents? found/) { 
               my $fragment = $1; 
               $fragments+=$fragment; 
               if ($fragment > 1) { 
                       $fragfiles++; 
               } 
               $files++; 

       } else { 
               print ("$res : not understand for $file.\n"); 
       } 
       close (FRAG); 
} 
close (FILES); 

print ( $fragfiles / $files * 100 . "% non contiguous files, " . $fragments / $files . " average fragments.\n");

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I have a different theory. The script causes fragmentation on reiserfs and then reports what it has done! :cheeky:

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Surely enough they are smoking something evil. In the past my fragmentation problems were way more severe with ext3 than Reiser 3.6 (never used Reiser 4, and I'll probably won't do it anytime soon). Currently using Reiser 3.6 exclusively (excluding a small, 32MB long /boot partition on my main desktop machine, which is ext2).

It may be a bit system dependent, but for partitions with many small files Reiser is ages more effective than ext3, while for large partitions containing mainly big files, xfs and jfs should be the most effective solutions.

Edited by scarecrow

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Bah you all!

 

http://ck.kolivas.org/faqs/audio_hints

 

the kernel developer says ext3 :P

 

I think a lot of fuss is made over nothing when it comes to ext3 and reiserfs, both work well, I've had no issues with either, and have used both extensively under heavy and light loads. Either way, I go with ext3, its tried and true.

 

iphitus

 

btw, no mentioning reiser4. really. dont. like, no. dont.

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Well, the script seems to run for me, but I get an error as shown below:

 

[root@europa Download]# ./reiserfrag.pl
Use of uninitialized value in concatenation (.) or string at ./reiserfrag.pl line 14.
19.7452229299363% non contiguous files, 153.356687898089 average fragments.

 

seems to finish though. Mysti, did you get this error too?

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