Hot Diggety! Patrick Boutilier was rumored to have written:
>
> We pay only about $8000 CDN for 2TB of RAID5 storage.

Hmm, what disk subsystem and model, if I might ask? We're looking at
two products - the Nexsan ATAboy2 and an equivalent one from Jetstor;
both are pretty much technically identical in all respects and costs
about USD $13,000, and looks great. But that's for a 1.6 TB setup (8x200)
with max usable about 1.2 TB in a RAID-5 + 1 hot spare setup.

Now I'm curious what exceeds that in usable capacity for much cheaper.

> >Tape solutions are easier and proably cheaper to scale, and since you'll
> >probably net a library adn drives anyways to handle the copy-storage pool,
> >you'll probably find that for larger environments, having primairy copies
> >on
> >tape does make sense.
>
> Except when you need to restore. Restore from disk is much faster than
> restore from tape. :-)

That depends on what type of tape library you have and how you've
configured TSM (such as setting up a separate stgpool just to hold the
directory information, for instance). For example, a LTO-2 drive can
read/write data at up to 35 MB/sec natively, and even more in compressed
mode. That usually gives it a pretty good run compared to RAID-5 disks :)
I usually see about 18-22 MB/sec with RAID-5 drawers from various vendors
and with various hardware-accelerated cache-based RAID controllers.

-Dan