[plug] JFS pros, cons?

[Craig Ringer]

> I'm going through the motions of setting up what I hope will be a high 
> availability Linux machine.   It will have a UPS, dual SCSI disks in 
> RAID-1 and tape backups will be made daily (and tested!)

*ouch* w.r.t to SCSI RAID. I'm using a 3ware Escalade 8500 8port SATA 
raid controller in our new linux terminal server box and its running 
/great/. 240g of RAID5 useable storage + 40g RAID1 useable storage for 
$2800 , and more than 1/3 of that the controller. If you need capacity, 
consider real hardware ATA or SATA raid instead of SCSI. OTOH this is 
new-ish hardware and we haven't been running it all that long, so I 
can't say "its perfect under long term high load" yet.

Also, this RAID controller can't hot-expand arrays, the array must be 
deleted and rebuilt, requiring a backup-and-restore cycle. It supports 
hot spares, hot array rebuilds from degraded state, hot-swap of SATA 
drives, and multiple arrays though so its sufficient to 90% of possible 
needs.

 > And so it
 > comes to the question of which file system to choose...

I've used both ReiserFS and Ext3 in production environments and haven't 
found the difference to be remarkable in stability or performance. I'd 
say reiser outperforms ext3 for most tasks, but in the real world its 
not all that noticeable. The only time I've ever had errors or failures 
from either FS, its turned out to be hard disk failure or motherboard 
problems.

I've never tried XFS or JFS - I'll stick to what's well tested /in 
linux/ unless I have a strong reason to use something else.

> In PLUGgers' experience, is Reiser the way to go?   XFS?   Something 
> else?   Given that I have RAID-1 and a UPS, would ext2 be good enough?   
> After all, I haven't had any problems with it over the years.

Ext2 is /never/ good enough IMHO. A UPS can't protect you from a kernel 
panic caused by failing hardware or some obscure bug - and if that 
happens while updating the FS directory information things could get 
ugly. I /have/ had corrupt ext2 filesystems requiring reinstall, that's 
what prompted me to switch to resiserfs at home as soon as 2.4.0 came 
out with it built in.

> My aim is to have the system boot from the RAID array and have the swap 
> partition in the RAID as well.   Do any of the file systems prevent 
> either of these happening?  In other words is it better to have swap as
> ext2, for example, the boot as Reiser and the root (and everything else) 
> as JFS?

Swap would be a dedicated partition ideally. While its possible to use 
swap files its slower and has race conditions associated that you'd 
prefer to avoid. I've used swapfiles to suppliment swap partitions, but 
wouldn't use a swapfile as my only swap.

Otherwise, it should be fine to have both swap and any normal 
filesystems on the same RAID array.

Craig Ringer