[PLUG] SCSI hardware recommendations, pointers

[Steve Bonds]

On 15 Aug 2002, Russell Senior seniorr at aracnet.com wrote:

> My old 18-gig narrow SCSI drive just filled up and I am ready to
> upgrade to current technology, something like the Ultra 160 stuff.  
> It is my analysis workstation, so good disk bandwidth is important.
> Because of our backup needs (need something we can haul off-site), I
> want to get something hot-swappable.  What do you recommend, and where
> can I find decent prices on it?

What level of hot-swap are you looking for?  If you want true hot-swap
Will your workstation have redundant drives (at least) so it doesn't get
stupid when the drive is removed?  Are you planning on redundant SCSI
cards so the inevitable bus reset that hits when the drive is removed
doesn't interrupt/cancel the I/Os outstanding to the other drive?

Are you only looking for "warm swap"?  This is where you quiesce the I/O
to that drive (i.e. unmount everything), remove the device from the kernel
("echo 'scsi remove-single-device 0 0 1 0' > /proc/scsi/scsi" for ID 1),
and then remove the device.  You might be able to avoid the SCSI bus reset
in this case and save yourself a card.

Unfortunately, my experience with hot-swap hardware vendors is limited, so
I can't actually give you the info you were looking for.  ;-)

  -- Steve

PS: Be sure to check the actual sustained media-to-interface transfer rate
on the drives if performance is a concern.  Ignore any "burst" or "cache
to interface" figures.  You'll never see those.  ;-)  The fastest drive I
know of is the Seagate Cheetah XP15, rated at 51-69MB/s
media-to-interface.

PPS: No, they're not cheap.  ;-)