[s-cars] NAC- need advice on photo workstation, RAID and some other ???s

[Taka Mizutani]

On 6/12/06, Theodore Chen <tedebearp at yahoo.com> wrote:
>
>
> --- Taka Mizutani <t44tqtro at gmail.com> wrote:
>
> > The reason for the RAID array is also for future expandability- I do
> foresee
> > hitting that 2Tb limit eventually.
>
> wow, that's a big home data center.  there was a time when you had to buy
> gigantic storage machines from IBM to store that kind of data.  now you
> can
> get 2TB for $800 (4 x 500GB HDs at $200 each).


Well, figure a 5400dpi film scanner will put out easy 20MB individual files,
I've got probably a good few hundred rolls of film to scan and restore
digitally.

I've also got several GB of digital photos as well. A few hundred Gb will go
away pretty fast, I think.

I was getting 320GB HDs for $100 each, will be about $120 now (that deal
went away). Makes for over 2TB for $700. The 500GB drives are rather
expensive IMO, still, esp. in SATA flavor.

however, if you want to add more drives, i think you'll have to add
> them as a group of 3 or 4 - same size as your initial group, configured
> so that you effectively make each of the original drives bigger, and
> it won't have the performance of an 8 drive array.  otherwise, you have
> to rebuild the volume and recalculate all the parities.  it probably
> depends on the features in your controller, but i don't think adding more
> capacity to an existing RAID array is as simple as plugging in a new
> drive.


I know that adding drives will require a rebuild, but the Promise and Areca
controllers  allow for a hot rebuild, hot swap, can do most functions on the
fly. Expansion is also available hot.

RAID 6 is overkill, IMHO.  you're going to take two drives for parity
> instead of just one as with RAID 5, and i don't think you're going to
> get much additional protection over a RAID 5 with Retrospect backups.
> RAID 6 guards against double disk failure, which is much less likely
> when you have a relatively small number of disks.  if you were going to
> run a 1000-disk farm, i could see using RAID 6, but you're talking about
> single digit numbers of disks.  it's hugely inefficient unless you have
> a large number of disks.


Point taken on the RAID 6- I'll just run a 4 drive RAID 5 with maybe a hot
spare.

Taka