[mythtv-users] Should I use LVM on this new raid?
bfoddy at visi.com
Mon Sep 24 03:10:01 UTC 2007
On Sunday 23 September 2007, Jay R. Ashworth wrote:
> On Fri, Sep 21, 2007 at 08:26:50PM -0500, Brian Foddy wrote:
> > 3ware 9650 8port raid card, and I'm starting out with
> > 2 x 1000GB HDs, initially I plan them in raid0. As
> RAID and LVM, like so many things, are religious issues.
> I *never* recommend RAID 0 to anyone; it was a hack to manage enough
> disk channel bandwidth for CPUs that were faster than the disks; these
> days, the disks are faster than just about any data you might have
> coming in... so RAID 1 or 5 them for safety.
> RAID 0 leaves you with the *product* of the MTBFs (which is to say, if
> one is .99 reliable and the other .98, then the resulting stripeset is
> .9702 reliable, and so forth) why waste MTBF?
> Evaluate carefully the relative cost of drives, as well, 5x500GB RAID5
> may give you the same amount of storage for less money then 2x1TB
> RAID0; the largest capacity *anything* is always more than twice the
> price of the next one down half its size.
> 500GB Seagate 7200.10s are about a bill right now.
Yes I know the risks of RAID0, I've lived with a 5x RAID0 for
probably 4-5 years now. As the budget allows, I'll add
a couple more drives and migrate it to raid5.
I was originally thinking the 500GB drives would be the way to
go, primarily because of the very attractive price/size ratio. That's
even why I paid extra for a 8 port raid card cuz I thought I'd
be in the 5-8 drive range. But when I started looking around
at other options there were a few factors that shifted my decision.
1. I discovered the new Seagate 1000GB drives are not just bigger,
they are much better. 32MB cache vs 16, and the internal throughput
is roughly 40% faster (~105 vs 70 (can't remember the units)). And
they use less power / run cooler. They are a whole new generation
drive vs even the 500/750GB perpendicular drives that are so cheap
2. Since I wasn't buying all the drives right up front, I tried to guess
what would be the drives I'd wish I had in 6-12 months, and what would
be the sweet price/size ratio at the time, knowing once you pick a
disk size in a raid, its very hard to change it unless you start a new
unit or replace all the old drives. This clearly pointed to the 1000GB
3. The final price on the new drives, was actually not that far out
of reach. New Egg has the ES.2 series 1000GB drives for $370 ea.
Within reason of the price/size of an older series 500 ES.1 drive.
These factors lead me to going with just 2 1000GB drives with
number 3 and maybe 4 sometime in the next few months. I doubt
the 2 drives will fail that soon, and even if they do, the data isn't
that critical right away.
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