[mythtv-users] question about RAID

Gavin Haslett gavin at nodecaf.net
Mon Jan 9 00:50:56 UTC 2006


RAID 0 would be a straight stripe with no data protection. You were
talking about three drives, so in order to use all three you'd be
talking this or a RAID 5 in order to get some modicum of protection.

If you wanted to go RAID 1 or RAID 0+1 then you'd need an even number of
drives, and total capacity would be half the actual aggregate capacity
of all those drives.

Note that in order to create your RAID you're going to have to re-
partition your existing disk... so a backup and restore is inevitable.

I know you said data protection is not an issue... but believe me when I
tell you that it can become an issue rapidly. You can build a
significant collection of recordings on any reasonable size media (I
have mirrored 160Gb drives myself), and there's no recovery if you lose
a single disk. It's not like you can cut the array down to half the
array and still get half your data back... you'll lose it all if one of
the drives in a RAID 0 fails. RAID 5 and RAID 1/0+1 would at least allow
you protection.

>From a sheer cost perspective I'd say RAID 5 is the way to go... but
bear in mind that the processing overhead of RAID 5 plus the data load
of reading and writing data and parity in a RAID 5 will make it slow,
especially since you run significant risk of saturating the PCI bus with
SATA.

My dual 160's work great for me right now, and if I wanted to expand I'd
just add another pair of drives and continue my RAID 0+1 I set up. I
have thought about buying a third and going RAID 5 (would double my
storage). Since I'm running ATA133 instead of SATA (drives were cheaper
at the time) I am not really stressed about saturating the bus... but my
poor old AMD 800 might not be happy with me ;)


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