[mythtv-users] OT: help selecting drives for server

[Brian Wood]

On Monday 18 May 2009 11:00:46 Nasa wrote:
> Hi,
>
>
> I'm sure questions like this come up all the time -- so I was hoping
> someone could give me some advise on this...
>
> I have a server that has a hardware raid card (I already had it, so plz no
> flaming on hardware vs software raid) which has 8 SATA ports.  I presently
> have 2 RAID-5 arrays setup for a total of 2.8T of space.  I have managed to
> come close to filling up the space and am looking to upgrade.  One array is
> made up of 3 drives (2x750GB, 1x1TB) and the other is made up of 4 500GB
> drives.  I would like to keep the number of times I have to rebuild this to
> as few as possible and the fewer the drives the better.
>
> I would like to use drives larger than 1TB, however, the 2TB drives are
> pretty pricey right now.  I'm not sure I trust the Seagate 1.5TB drives
> (any one have comments on them?) and WD says it's desktop edition drives
> are not appropriate for RAIDs (they suggest the Raid Editions for more
> $$$).  And I don't really now much about the Hitachi drives...
>
> So I was hoping someone out there has some suggestions on which way to
> go...

I'd be curious as to why WD doesn't suggest using the cheaper drives for RAID 
systems, other than the obvious fact that most RAID systems are used in 
enterprise systems where the user can afford to pay more.

Hitachi has a lot of adherents these days, but I still remember the problems 
back when that division belonged to IBM.

I'd also stay away from the Seagate 1.5s, the problems are supposedly solved, 
but it's hard to know how long a vendor has had them on the shelf, and I'd 
rather not fool with having to update firmware. When I buy a drive I figure 
it ought to be ready to go, not be a test platform for beta firmware.

Most Myth users do not spin enough drives to have statistically valid data, 
unless they do so at work.

I'd really consider H/W vs. S/W raid, what do you plan to do if your 
controller fails? Most H/W RAID cards I've seen require identical drives, I'm 
curious about your 750/750/1000 array, are you throwing away 250GB of the 
large drive?

Does your H/W RAID controller allow different-sized drives? Does it use 
partitions and not entire drives? Is it a PCI-X interface? What sort of card 
is it? A 32-bit card could have problems with 8 drives at once, most non-RAID 
8-port cards are either PCI-X or PCIExpress for that reason.

I just went through the H/W vs. S/W RAID issue, and I wound up using an 8-port 
PCI-X card (SuperMicro AOC-SAT2-MV8, only $99) and software RAID, even though 
I had hardware RAID controllers.

The real question is why are you using RAID? LVM or storage groups allow 
on-the-fly expansion. RAID is NOT a substitute for regular backups, as many 
folks have discovered to their loss.

Actually this question does not come up all that often, the best solution 
depends a lot of what your individual requirements are, what other tasks the 
array might be doing, what you have on hand and what you can get cheaply, so 
the best answer really depends on the individual user's particular situation.

The only thing I can say for sure is that no matter what you do, there will be 
a better and cheaper answer 6 months from now.

-- 
beww
beww at beww.org