Choosing the right RAID was Re: [ILUG] Wee nas box

[Brendan Minish]

On Fri, 2009-11-20 at 11:18 +0000, Gavin McCullagh wrote:

> I recently asked this question of a techie/sales guy who looked at me as
> though I had 5 heads (he was pushing a 3-drive RAID5 unit).  As far as he
> was concerned, RAID5 is _the_ industry standard and he had never seen a
> problem (beyond the usual single drive failure) in the countless installs
> he had been involved in.

Good for him.. of course sales is at a distance from the coalface.. 

> Is this a real concern?  In terms of a budget, in some instances you could
> probably use SCSI drives in RAID5 to achieve the same capacity as SATA
> drives in RAID1.

Yes I have had raid 5 systems fail during rebuilds on 2 occasions (1 was
using a hardware controller that 'helpfully' hid the smart status from
the OS) the other was software based and I had a second drive fail
during the rebuild.
 Since I am not responsible for very many raid arrays this seems like a
high average (or perhaps I am just careless..) but for me it's Software
Raid 1 and Raid 10 from here on in. 
I have always backed up RAID disks and will continue to do so. 

Of course there are no guarantees that raid1 won't fail during a rebuild
either but at least you have better odds and you are not stressing the
drive nearly as much with a raid1 rebuild, the performance won't be as
shit during the rebuild either  

.brendan