[mythtv-users] RAID using two drives per PATA channel ?

Steven Adeff adeffs.mythtv at gmail.com
Tue Aug 1 21:21:33 UTC 2006

On 7/31/06, Brad Templeton <brad+myth at templetons.com> wrote:
> On Mon, Jul 31, 2006 at 06:08:50PM -0700, Brad Templeton wrote:
> > On the other hand, high performance is desired for your regular linux
> > partitions.   They are of course much smaller.  You might consider
> > raid 1+0 on 4 drives for them, and raid-5 on 4 drives for the video
> > files.   (Software raid, typically for this ability.)
> Whoops, I should add that if your raid 1+0 is done with master/slaves
> it could take the hit there.   A Raid 0 (stripe) done to 2 drives, both
> masters, would be happy but that's not redundant.   A raid where you
> stripe over controllers and mirror over slaves would be slower on write
> that having 4 dedicated controllers, but presumably just as fast on read.
> As for one drive locking out the other one, if you fear that, then
> this is not for you, but you're not trying to build servers for ebay
> here, it's a tv recorder.  For me, I can handle if the system hangs
> as long as I can recover all my data after I attend to it.

so many messages to reply to....

so obviously this is for a myth recordings drive. My main thing is
that I've got a dedicated backend with a nice case that has a drive
bay for 6 hdd's. (plus one system drive and a few CDRom drives, but
the drive bay has built in cooling via 2 huge fans, so I'll limit
myself to 6 drives). I figure, since I have the space and the ability
in one form or another to have a 6 drive RAID 10 array for recordings,
whats the best way to go about it from where I am....
I've currently got 2 SATA drives (using the only two SATA ports on my
mobo), and 2 ATA100 drives using two individual channels on a Promise
ATA100 PCI card.

all four drives are identical models except for the ATA/SATA electronics.

so, I could go the cheap route and just buy two more ATA100 drives,
place them on the Promise ATA100 controller and be done with it. this
will obviously add space to the array (and yes, I know I'll most
likely have to blank the entire array, not a concern for me), but will
it hurt or hinder the performance? Its not that I can't take the more
expensive route and buy 4 SATA drives and a new mobo/SATA controller,
as I know this would gain speed.

as for reliability, well, unless I get an individual controller card
for each drive, in my opinion it doesn't matter. If the card fails,
you need a new card, if one drive fails and that brings the entire
array down temporarily, replace the drive and rebuild. the only
advantage is if a cable fails, though from what I understand this is
the least likely point of failure, and has a small percentage of
failure, so it can essentialy be ignored.

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