[mythtv-users] question about RAID

David myth at dgreaves.com
Tue Jan 10 09:11:13 UTC 2006


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raidtab is obsolete with newer md.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



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