The Belgain

Which filesystem?

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Hi there,

I'm putting together a large software RAID5 array, and was just wondering what filesystem I should use? I'm using EVMS to manage it, and this is on an Ubuntu Breezy install; all the main filesystems are available on it (EXT3, Reiser, JFS, XFS, ...).

I'm not really that bothered (within reason) about performace as this is just going to be accessed over a network - mainly for streaming audio/video. What I do need however is:

- stability: I want to be as sure as possible that there's no chance of data corruption occuring.

- it's got to be possible to expand the filesystem while keeping the data on it intact (I don't need it to be able to do this while mounted though).

- ideally it should be possilbe to have very large partitions on it (it'll be only 1TB for now, but could conceivably become > 2TB).

At the moment I'm thinking that plain old EXT3 may be best (especially for stability). Am I right in thinking the maximum size of the array is ((2^32) * chunk_size)?

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not much of a help except saying what I use

5x160GB maxtors (4 on a promise TX4000, 1 on mobo IDE channel) on fedora4. Using LVM and XFS - had no problems at all, no corruption that I found (knock on wood) and I like XFS' features - quick online expansion, filesystem dump and snapshots are usefull for backups (rsync to external hdd with snapshots is what I use)

I did not want reiser as the old one was no longer developed I think and the new one I did not find ready for prime time, at least about 6-7 months back, maybe longer I forget. JFS(2?) I never looked much into, seemed to be not really so heavily popular with Linux crowd and I seen too much problems due to JFS2 on AIX in work so I wanted to stay away from it :)

Ext3 - dunno, I never liked ext2 that much anyway, it's a very basic filesystem IMHO and it works but, just I did not want it :)

my performance with this setup is quite nice - usually a ~38MB/s sustained during a sequential write from an internal hdd on different channel (at least that is what mc is reporting :), I never done much of timed tests) - ~23MB/s from/to a fireware400 connected hdd, which I think pretty much a limit of the interface/chipset used.

never had a problem with XFS/LVM, very good options IMHO. One thing to look for with lvm is the extent sizes, as the default value is too low, not sure now as it was a while ago when I setup the array and I forgot the details and too lazy to read the man pages. Smallest files on my array are about 200KB and generally I use it as filedump, so XFS' optimization for larger filesizes is good, quite a few GB+ files are on the array too.

Is EVMS still so stupidly complex like it was in the past? I was stumpled how strange it's to use, maybe I'm too used to lvm

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I would go with either EXT3 or XFS. It doesn't really matter. EXT3 has the edge with respect to some tools --better and easier data recovery if something goes wrong.

I wouldn't use Reiser3 or JFS. Both are obselete. I actually use Reiser4 on my home fileservers, but that's more work because the kernel maintainers haven't integrated it into mainline, and, while its stable and solid by all accounts, it is still relatively new.

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- stability: I want to be as sure as possible that there's no chance of data corruption occuring.

- it's got to be possible to expand the filesystem while keeping the data on it intact (I don't need it to be able to do this while mounted though).

- ideally it should be possilbe to have very large partitions on it (it'll be only 1TB for now, but could conceivably become > 2TB).

Not an option for you since you run Ubuntu,

I am anxiously waiting for ZFS on Solaris Express, any minute now ...

http://blogs.sun.com/roller/page/bonwick?e...he_last_word_in

Everyting looks fantastic, on paper at least :)

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Not an option for you since you run Ubuntu,

I am anxiously waiting for ZFS on Solaris Express, any minute now ...

http://blogs.sun.com/roller/page/bonwick?e...he_last_word_in

Everyting looks fantastic, on paper at least :)

218230[/snapback]

I'm watching for ZFS like a hawk in the Express releases too. Earlier I was trying to figure out how something particular to raid5 worked, and looked at raid5.c in the Linux kernel and raid.c in the OpenSolaris kernel, and was stunned at how much cleaner-looking (based on an admittedly quick 15-minute skim of each) the latter is.

silent - do you think you could do a Bonnie++ run on your array to eliminate the additional disk as a variable? I'm interested in building something similar, and wondering about which parts to use. What type of CPU and chipset are you using?

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Thanks for the replies guys. I think I'll probably just be sticking with EXT3 as it's pretty tried and tested. I don't know how justified they are, but there seem to be many posts about data corruption on Reiser and some other filesystems, so I'll stay away from them...

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personally I use XFS. The problem with ext3 is that is has by far the worst performance of the journalling file systems, which does affect me when using mythtv (file deletes take too long).

reiser4 is far too knew to know whether it is stable yet, reiser3 is probably stable enough now.

JFS came from OS/2 not from AIX so needed a lot of recoding.

XFS was a very simple conversion from IRIX, most the work was in writing the features needed in the linux kernel. (I believe most the added kernel features are used by all the journalling file systems.)

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personally I use XFS. The problem with ext3 is that is has by far the worst performance of the journalling file systems, which does affect me when using mythtv (file deletes take too long).

218338[/snapback]

Sounds like a MythTV issue (too). It shouldn't block the interface during the delete operation.

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personally I use XFS. The problem with ext3 is that is has by far the worst performance of the journalling file systems, which does affect me when using mythtv (file deletes take too long).

218338[/snapback]

Sounds like a MythTV issue (too). It shouldn't block the interface during the delete operation.

218339[/snapback]

I better clarify the mythtv issue, the fact it takes more than 1 second to delete a 2 GB file means if mythtv is recording a file at the same time the recording hicups (not all the data is written to the disk.) I see this as more of a OS/filesystem problem than a mythtv problem. The deletes happen almost instantly on XFS.

Edited by Hairlocks

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