[mythtv-users] question about RAID

Steve Adeff adeffs at gmail.com
Tue Jan 10 14:57:07 UTC 2006


On Tuesday 10 January 2006 04:11, David wrote:
> James C. Dastrup wrote:
> >>>mdadm RAID 0 with 3 drives, JFS (my favorite) or XFS file system.
> >>>
> >>>Some may disagree, but in such a simple setup, I don't see any reason to
> >>>add lvm on top of this RAID array, but others may prefer it.
> >>>
> >>>Also note, I don't believe you can boot off of a md RAID 0 drive, so
> >>> you'll need another driver (or network boot) for your boot partition.
> >>
> >>Ok, thats what I thought. do I have to use any special mdadm settings in
> >> order to do RAID0 and have it stripe across the drives?
> >
> >Nothing special. Just a /etc/raidtab like so:
> >
> ># /var/video (RAID 0)
> >raiddev                 /dev/md0
> >raid-level              0
> >nr-raid-disks           2
> >chunk-size              32
> >persistent-superblock   1
> >device                  /dev/hda1
> >raid-disk               0
> >device                  /dev/hdc1
> >raid-disk               1
>
> Don't do this.
>
> You shouldn't mix raidtab and mdadm
> raidtab is obsolete with newer md. Uninstall it.
>
> using mdadm the above would be:
> mdadm --create /dev/md0 --chunk=32 --level=raid0 --raid-devices=2
> /dev/hda1 /dev/hdc1
>
> I suggest reading man mdadm (and why are you setting chunk to 32?)
>
> If you decide to go raid5 then you *must* use mdadm -F (otherwise you
> may well miss a disk failure - it's easy to do). Of course if you use
> raid0 this isn't important since you'll spot a drive failure as soon as
> the system crashes ;)
>
>
> David

David, 

do you have a good source of reading on mdadm other than the Software RAID 
HOWTO? I'm going to be setting up my RAID5 across 3 drives today and want to 
make sure I do it correctly.

-- 
thanks!
Steve


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