To start out with, if all you need is six hot-swap drives without regard to
size pick up an old server off of ebay--I have an IBM Model 95 with 6 SCSI
drives, a RAID controller, an Ethernet card, a Token Ring card, and not one
but two FDDI boards, that I got off of ebay for less than the price of an
SATA hot-swap cage--it even came with a 500 user copy of Novell and a bunch
of financial data on a defunct company installed said:
What's the cheapest way to setup a bunch of drives in removeable trays
in a tall tower. Internal Firewire enclosures seem to be spendy. I
want about 6 Internal drives that are all hot swappable.
You have four issues, the controller, the drives, and the enclosure, and the
operating system or drivers.
The enclosure's the easy part--for about $130-1700 you can get hot-swap
enclosures that fit four or five 3-1/2" LP SATA, SCA, or IDE drives into
three 5-1/4 half-height bays. SATA and SCA (aka 80-pin SCSI) are preferred
as the standards for both provide for hot-swap support on the drive--with
IDE the enclosure has to provide the hot-swap support. Just froogle "hot
swap cage" and you'll find a zillion of them. Since the prices are about
the same and the functionality is about the same, the enclosure isn't going
to drive the costs.
You need a host adapter that supports the number of drives you want and
supports hot-swap. Most but not all SCSI host adapters do support
hot-swap, but read the specs. Any SCSI host adapter can handle your six
drives. Most IDE host adapters do _not_ support hot-swap--you need one of
the higher priced RAID controllers to get that functionality--again read
the fine print--the 3Ware and some Promise models do, but the Promise
models that support hot-swap are priced in the same ballpark as the
3Wares--you'll also need a host adapter that supports 6 drives unless you
have extra IDE channels on your motherboard. While the SATA standard calls
for hot-swap support, if you read the fine print on SATA host adapters and
chipsets you'll find that some of them do not comply with that portion of
the standard (boo hiss) so you'll have to choose carefully. You'll also
need a host adapter that supports 6 drives--I don't know of any
motherboards that have 6 SATA ports, so even if you do have onboard SATA
you'll need an additional host adapter.
The drives are the easy part--any drives that fit in the enclosures and plug
into the connectors will be fine--just remember that to get 5 drives in
they have to be "LP" which is the 1 inch high drives, not the 1.6" high
drives that can be had cheaply on ebay sometimes--with 1.6" drives you'll
generally only be able to get 2 drives in--you'd think that you could get 3
in but the slots in the cages aren't spaced to allow that (some Dell
servers have slots for both sizes--they _can_ get 3 of the taller drives
in).
Even if all the hardware supports hot-swap, the operating system or drivers
need to as well--with redundant hardware RAID it's an internal issue for
the RAID, the operating system never "sees" the replacement. With separate
disks or software RAID the OS needs to support either directly or via a
driver hot-swapping the drive in question, otherwise it's going to get
confused when the contents change. Again whatever you go for check this
before you buy.
