[mythtvnz] File System for RAID-5

[Robin Gilks]

> Quoting Robin Gilks <g8ecj at gilks.org>:
>
>>
>>> Having just had a near-death experience with my non-RAID LVM system
>>> for Myth, I am about to convert everything to a RAID-5 setup (software
>>> RAID) with LVM on top. Before I go ahead does anyone have any
>>> recommendations on best choice of file system to use, given that it
>>> will be within LVM on RAID-5? I was going to go with XFS, but that
>>> cannot be shrunk, which (as I have found) can be very irritating when
>>> trying to reorganise your disks in an LVM. I know there are a bunch of
>>> hot new file systems out now, but I? wary of trying something new in
>>> an a setup like this.
>>
>> Having just this last week built a replacement for my 6 year old server,
>> I've basically used the same scheme again.
>>
>> Huge raid5 array (the definition of huge is now very different to what
>> it
>> was 6 years ago!!), LVM2 over the top, recordings and video partitions
>> with jfs (large files but not many of them) and ext3 for all the other
>> partitions (email, music etc). The system disk is separate and gets
>> regular backups into an external device, most of the stuff on the raid
>> array is expendable but by using smartd and mdadm I get an email if
>> something starts to fail.
>>
>> Interesting that the new box is 10 times faster, has 5 times as much
>> disk,
>> 4 times as much ram and consumes less than half as much power...
>>
>>
>> --
>> Robin Gilks
>>
>>
> Hi Robin,
>
> This will be dedicated to Myth media files, so want something suited
> to large media files. Raid size is 3TB. Any particular reason you went
> for JFS over, say, XFS or others?

I choose jfs for the really large partitions because if there is the need
for a journal playback due to a back shutdown (kicking the plug out the
back was the last one!!) the rebuild is VERY much faster than with ext3.

I'm spinning 5TB in a raid5 (all the sata slots used now) but the old box
ran 4x200G and I had a failure with that. msadm sent me the email, I got
another drive, fdisk'ed it and a few hours later the array was rebuilt
with only about 10 minutes downtime (no lost recordings, good WAF) to
physically change the drive.

This time round I'm not bothering with the raid1 system disk, I'm just
doing regular backups to an external 1T drive - if that goes then new
disk, live CD, restore and off we go - which reminds me I must check that
I have a bootable CD with dar on it :-)


-- 
Robin Gilks