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Sith_Happens Veteran
Joined: 15 Dec 2004 Posts: 1807 Location: The University of Maryland at College Park
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Posted: Mon Apr 25, 2005 4:47 pm Post subject: What's the most space efficient journaled filesystem? |
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Here is a question that I've been puzzling over recently, what is the most space efficient journaled filesystem? On smaller filesystems, the space sacrifice for a filesystem journal is not that significant, but when you get start dealing with big partitions, it really adds up. So below you'll see I've done some tests using a 1.5 gig partition, the latest versions of all related filesytem utilities as well as df and fdisk. From the looks of it, it seems that JFS and XFS have a leg up on ReiserFS, (look at the joural sizes). I'm not saying this is definitive proof of anything though, in fact I expect that some of these disparities probably arise from the different approaches all the filesystems take, so feel free to bash my meathods . I'd like people to try to explain these differences on an empty partition, as well as offer some useful figures on actual effeciency on a full partition (quantative evidence would be nice). I'm also a little confused as to why the available space according to df on the ext filesystems seems to be so low, it looks to me like some kind of measurement error in df.
Code: | #############################################
Filesystem Space Efficiency
(df size / fdisk size)
ext2 0.961189
ext3 0.961189
XFS 0.969739
JFS 0.972310
ReiserFS 3.6 0.976482
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Filesystem Journal Size
(df Used on empty partition)
ext2 N/A (20 kb used in case anybody is interested though)
ext3 32828 Kb
XFS 144 Kb
JFS 312 Kb
ReiserFS 3.6 32840 Kb
#############################################
Filesystem Journal Size
(indexed against ext2)
ext2 1
ext3 1641.4
XFS 7.2
JFS 15.6
ReiserFS 3.6 1642
#############################################
Filesystem Journal Efficiency
(df available / df size)
ext2 N/A
ext3 0.977310
XFS 0.999901
JFS 0.999787
ReiserFS 3.6 0.977657
#############################################
Filesystem Overall Efficiency
(df available / fdisk size)
ext2 0.912347
ext3 0.890551
XFS 0.969643
JFS 0.972101
ReiserFS 3.6 0.954669 |
_________________ "That question was less stupid; though you asked it in a profoundly stupid way."
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codergeek42 Bodhisattva
Joined: 05 Apr 2004 Posts: 5142 Location: Anaheim, CA (USA)
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Posted: Mon Apr 25, 2005 6:44 pm Post subject: Re: What's the most space efficient journaled filesystem? |
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Sith_Happens wrote: | I'm also a little confused as to why the available space according to df on the ext filesystems seems to be so low, it looks to me like some kind of measurement error in df. | By default, Ext2 and Ext3 reserve something like 5% of the available filesystem blocks for the superuser (root). You can change this with tune2fs though: Code: | # /sbin/tune2fs -r ${HOW_MANY_BLOCKS_TO_RESERVE} /dev/${PARTITION} | Or alternatively Code: | # /sbin/tune2fs -m ${RESERVED_BLOCKS_PERCENTAGE} /dev/${PARTITION} | Hope that helps.. _________________ ~~ Peter: Programmer, Mathematician, STEM & Free Software Advocate, Enlightened Agent, Transhumanist, Fedora contributor
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GungHo Apprentice
Joined: 27 Aug 2004 Posts: 254
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