ext2 or ext3 for large RAID array

TomB17 · 2010-06-26 00:58:12

I'm just in the process of creating a 10TB array of 5 x 2TB drives.

I've been burned too many times by EXT4 so it's out for the forseable future.

My concern is the crazy amount of time required to stabalize the file system when periodic checks are mandated. I'm using ext3 right now on a 7.5TB file system and have tuned the auto checking down to 2 years and 100 mounts. It's not the best situation but when the system goes down due to over heating (filter plugs every few months), I turn it on, and it goes into a 2 day recovery procedure during the boot process, it's outside the envelope of acceptibility.

Last edited by TomB17 (2010-06-26 02:32:55)

TomB17 · 2010-06-26 15:04:51

For what it's worth, I went XFS despite a personal history with it that isn't entirely positive. It's been a long, long time since I've used it so I expect it has evolved into something nice and stable.

SiC · 2010-06-26 16:06:41

You could also try ReiserFS rather than Ext3 or 4. It's well supported and I've found it entirely reliable.

graysky · 2010-06-26 16:18:35

Not what you asked but can you describe how you have been burnt by ext4? Since 2.6.30, it has been very good in my opinion.

Last edited by graysky (2010-06-26 16:32:35)

TomB17 · 2010-06-26 17:06:41

I appreciate the comments, gentlemen.

graysky wrote:

Not what you asked but can you describe how you have been burnt by ext4?

I've been burned by the 0 byte file bug. The files were all there but some of them went to 0 bytes.

I did that on a backup array about 6~8 months ago. Thinking, "It's just a backup array", I tried EXT4 for the first time. It formatted up nicely, 36 hours of rsync, and I was good to go. I didn't realize I had the 0 byte file issue until my main array had some issues. When I went to the backup array, there were tons of 0 byte files, including fstab, and mdadm.conf. That made it more difficult to rebuild the main array. I did manage to rebuild the main array. Once done, I formatted the backup array EXT3 and I've been hessitante to experiment with filesystems.

The 0 byte file bug is well documented, and perhaps long solved, but I'm not ready to get back on that bandwagon.

For what it's worth, I was burned by EXT3 several times early in it's existance. That was a different issue. The whole filesystem would become corrupt after a while. It was disasterous but I didn't count on my PC then the way I do now. That was back in the days I could back up to CD-ROM. I kept at it and eventually EXT3 stabalized. These days, I trust EXT3 with my life.

Last edited by TomB17 (2010-06-26 17:08:37)

graysky · 2010-06-26 18:32:21

Sounds like you wanna use ext3 then...

synthead · 2010-06-26 20:06:09

Yeah for your own peace of mind, ext3 is probably the most reliable linux filesystem. I use ext4 exclusively now and haven't had any problems. I also use reiserfs for /var for a big speed bump with pacman, but I have had data loss with power failures by using it. Kinda ugly.

You can turn off filesystem checks in the fstab, specify "0 0" at the end of your mount line. It would be a good idea to do these when you find it convenient, though (as you know).

rusty99 · 2010-06-26 20:13:53

TomB17 wrote:

I appreciate the comments, gentlemen.
graysky wrote:
Not what you asked but can you describe how you have been burnt by ext4?
I've been burned by the 0 byte file bug. The files were all there but some of them went to 0 bytes.
I did that on a backup array about 6~8 months ago. Thinking, "It's just a backup array", I tried EXT4 for the first time. It formatted up nicely, 36 hours of rsync, and I was good to go. I didn't realize I had the 0 byte file issue until my main array had some issues. When I went to the backup array, there were tons of 0 byte files, including fstab, and mdadm.conf. That made it more difficult to rebuild the main array. I did manage to rebuild the main array. Once done, I formatted the backup array EXT3 and I've been hessitante to experiment with filesystems.
The 0 byte file bug is well documented, and perhaps long solved, but I'm not ready to get back on that bandwagon.
For what it's worth, I was burned by EXT3 several times early in it's existance. That was a different issue. The whole filesystem would become corrupt after a while. It was disasterous but I didn't count on my PC then the way I do now. That was back in the days I could back up to CD-ROM. I kept at it and eventually EXT3 stabalized. These days, I trust EXT3 with my life.

I encountered very similar issues, which resulted in me switching this workstation to FreeBSD and using ZFS for my raid arrays.
The beauty of that file system far outweighs anything available on Linux at this current time.

thisllub · 2010-06-30 09:36:40

rusty99 wrote:

I encountered very similar issues, which resulted in me switching this workstation to FreeBSD and using ZFS for my raid arrays.
The beauty of that file system far outweighs anything available on Linux at this current time.

I have to agree.
Even a basic FreeNAS USB booted system provides a ZFS system that can support snapshots out the wazoo.

However it needs a fast system to get the most out of it.
I set up hourly / daily / weekly snapshots and it ran out of steam over 400 GB on a 2G celeron D with 200G of ram even though only about 100Mb of changes an hour were pushed to it.

It led me to a more conservative approach but I have 3 of these machines so I still get my anal backup strategy.

On Linux I would probably go with Reiser 3.
For stability I can't split it with ext3 but it has many more features.

Last edited by thisllub (2010-06-30 09:38:59)

Arch Linux

#1 2010-06-26 00:58:12

ext2 or ext3 for large RAID array

#2 2010-06-26 15:04:51

Re: ext2 or ext3 for large RAID array

#3 2010-06-26 16:06:41

Re: ext2 or ext3 for large RAID array

#4 2010-06-26 16:18:35

Re: ext2 or ext3 for large RAID array

#5 2010-06-26 17:06:41

Re: ext2 or ext3 for large RAID array

#6 2010-06-26 18:32:21

Re: ext2 or ext3 for large RAID array

#7 2010-06-26 20:06:09

Re: ext2 or ext3 for large RAID array

#8 2010-06-26 20:13:53

Re: ext2 or ext3 for large RAID array

#9 2010-06-30 09:36:40

Re: ext2 or ext3 for large RAID array

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