JFS disadvantages

obsrv · 2008-09-29 11:17:41

What are JFS disadvantages? I now want to mirror ArchLinux and I'm choosing JFS.

SkonesMickLoud · 2008-09-29 11:30:23

http://wiki.archlinux.org/index.php/JFS

Ashren · 2008-09-29 12:29:48

The biggest disadvantage IMO is that a you can not shrink a JFS partition. If it's possible now please let me know.

kclive18 · 2008-09-29 12:56:21

JFS in general is the fastest-performing file system on Linux, which is why I chose it for my laptop and its 4200-rpm ATA6 hard disk. But yes, the fact that you cannot shrink it means that you have to make it smaller in the first place if you are dualbooting with another OS.

SkonesMickLoud · 2008-09-29 12:56:29

Ashren wrote:

The biggest disadvantage IMO is that a you can not shrink a JFS partition. If it's possible now please let me know.

You can, but it's really risky.

Also, JFS doesn't journal personal files, so you can lose some data after a crash/hard reboot.

kjon · 2008-09-29 18:26:29

As personal experience, JFS seemed to my quite slow. It saves a lot of cpu time (and, therefore, battery life) but at expense of high latencies when writting. It's a matter of taste. Is a rock solid filesystem, but too slow for me. (*)

(*) Custom setup constraints might apply

obsrv · 2008-09-29 18:27:30

this is off-topic but how about ext4? is it better than jfs?

freakcode · 2008-09-30 01:09:23

kclive18 wrote:

JFS in general is the fastest-performing file system on Linux

No claims without numbers

Anyway, performance varies deeply. Popular belief is that Reiser is faster for lots of small files, XFS is faster for lots of big files, Ext3 is balanced, and JFS is balanced like Ext3 but uses less CPU, though slows down with much files.

(Benchmarks apreciated!)

theringmaster · 2008-09-30 01:31:03

I use jfs on my desktop and I haven't had a problem with it. I have had a LOT of power outages here and I'm doing ok.

kensai · 2008-09-30 01:31:49

freakcode wrote:

kclive18 wrote:
JFS in general is the fastest-performing file system on Linux
No claims without numbers
Anyway, performance varies deeply. Popular belief is that Reiser is faster for lots of small files, XFS is faster for lots of big files, Ext3 is balanced, and JFS is balanced like Ext3 but uses less CPU, though slows down with much files.
(Benchmarks apreciated!)

Not even benchmarks can be reliable when it comes to File Systems, I have seen benchmarks where XFS wins, others in which JFS wins and yet others where ext3 or reiserfs wins. there is really no benchmark that can be reliable when it comes to file systems.

BTW, I use JFS. Nothing bad to say about it.

freakcode · 2008-09-30 02:31:55

kensai wrote:

freakcode wrote:
kclive18 wrote:
JFS in general is the fastest-performing file system on Linux
No claims without numbers
Anyway, performance varies deeply. Popular belief is that Reiser is faster for lots of small files, XFS is faster for lots of big files, Ext3 is balanced, and JFS is balanced like Ext3 but uses less CPU, though slows down with much files.
(Benchmarks apreciated!)
Not even benchmarks can be reliable when it comes to File Systems, I have seen benchmarks where XFS wins, others in which JFS wins and yet others where ext3 or reiserfs wins. there is really no benchmark that can be reliable when it comes to file systems.
BTW, I use JFS. Nothing bad to say about it.

Of course, because depends on what the benchmark is actually testing (read/write times, latency, troughput...). You won't find the better, but what are the cons and pros of each one.

Any numbers that can come up are better to discuss, so we avoid talking from perception.

kensai · 2008-09-30 02:59:37

Oh, and if you are going to use JFS, append elevator=deadline to your kernel line in grub/menu.lst. It is in the wiki.

Cotton · 2008-10-19 01:04:39

Whilst its been fine in operation (fast, low cpu etc like it says on the tin), I've almost always had problems following power outages, on a number of disks over the last 4 years.
Generally the fsck runs ok at the next boot following an unclean shutdown and everything appears ok, but then key programs like pacman & X have failed to run, indicating that some critical disk sector has been lost. Reinstalling the relevant applications has not generally been an available option, resulting in a total OS reinstallation

Ashren · 2008-10-19 07:50:06

SkonesMickLoud wrote:

Ashren wrote:
The biggest disadvantage IMO is that a you can not shrink a JFS partition. If it's possible now please let me know.
You can, but it's really risky.
Also, JFS doesn't journal personal files, so you can lose some data after a crash/hard reboot.

I'm willing to take the chance. How can I shrink a JFS partition?

cwjiof · 2008-10-19 09:26:21

There's no defragmentation command for a JFS file system, while XFS has.

theringmaster · 2008-10-19 15:19:43

Ashren wrote:

SkonesMickLoud wrote:
Ashren wrote:
The biggest disadvantage IMO is that a you can not shrink a JFS partition. If it's possible now please let me know.
You can, but it's really risky.
Also, JFS doesn't journal personal files, so you can lose some data after a crash/hard reboot.
I'm willing to take the chance. How can I shrink a JFS partition?

You can't, you can only think ahead as to what you want to do.

Zibi1981 · 2008-11-21 21:49:44

cwjiof wrote:

There's no defragmentation command for a JFS file system, while XFS has.

Can't one use i.e. shake for that?

iBertus · 2008-11-22 03:59:03

I'm using JFS on both my laptop and workstation. I like the lower CPU usage that tends to come along with JFS for my laptop. On my workstation, I've got a 6*750GB SATA disks in RAID10,f2 and so JFS performs well enough.

kensai · 2008-11-22 04:02:45

Zibi1981 wrote:

cwjiof wrote:
There's no defragmentation command for a JFS file system, while XFS has.
Can't one use i.e. shake for that?

good luck with that, you are going to need it, defrag from con kolivas nor shake ever reduced any fragmentation for me, not even a bit. I am now using fidefrag, is in aur, though I never got that to compile so I just downloaded it directly with bzr and installed its dependencies. It is working like a champ, I am planning on doing an article on it, with real proof of its effectiveness.

Zibi1981 · 2008-11-22 20:50:33

Never heard of fiDefrag. Thx for the tip. I will surely give him a try

Last edited by Zibi1981 (2008-11-22 20:53:10)

cerbie · 2008-11-23 03:53:39

Ditto. That's been my only real complaint against JFS--I hadn't found a working defragger. I'll check it out by manually doing dependencies, tonight. A more minor complaint being that I don't see any options to change the log size after formatting (my / is small, but has more than it needs for /, so maybe could use a bigger one).

So far (definitely more than 10 abrupt shutdowns due to wall power), recovery after bad shutdowns has been ideal. I've yet to lose, or find corrupted, files on my disks. I've had config files I was editing, and FF sessions, get rolled back. EXT3, even in journal mode, has caused loss of an entire partition (twice before in wirteback, so I got anal; but, then it did it with journaled mode!). fscking and testdidking only copies, even finding the alternate superblocks...only small amounts of files recovered. If I lose the ability to boot, or maybe fully login, but still have most of my data intact, easily accessible from a working computer, I'll manage. It will also allow me to stay cheap, and not get a UPS .

I intentionally have fairly slow drives, and have not noticed any FS performance differences between EXT2, EXT3, RFS, or JFS, as long as I use Deadline w/ JFS.

P.S. no file is currently above fidefrag's threshold, so *shrug*. I guess I'll just have to wait a few months to really see.
P.P.S. de-fragged several files on my backup drive, also JFS. Yay.

Last edited by cerbie (2008-11-24 12:52:06)

Arch Linux

#1 2008-09-29 11:17:41

JFS disadvantages

#2 2008-09-29 11:30:23

Re: JFS disadvantages

#3 2008-09-29 12:29:48

Re: JFS disadvantages

#4 2008-09-29 12:56:21

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#5 2008-09-29 12:56:29

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#6 2008-09-29 18:26:29

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#7 2008-09-29 18:27:30

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#8 2008-09-30 01:09:23

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#9 2008-09-30 01:31:03

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#10 2008-09-30 01:31:49

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#11 2008-09-30 02:31:55

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#13 2008-10-19 01:04:39

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#14 2008-10-19 07:50:06

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#15 2008-10-19 09:26:21

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#16 2008-10-19 15:19:43

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#17 2008-11-21 21:49:44

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#18 2008-11-22 03:59:03

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#19 2008-11-22 04:02:45

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#20 2008-11-22 20:50:33

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#21 2008-11-23 03:53:39

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