[rescue] Apple Announces Rackmount Server - WITH IDE HARDWARE RAID

[Joshua D Boyd]

On Wed, May 15, 2002 at 01:47:53PM -0400, Greg A. Woods wrote:

> > IDE is certainly going to be cheaper, but I'd be willing to bet that you
> > could put together an U160 SCSI setup with only 4 drives that would
> > knock the socks off of this thing in terms of access speed and data
> > throughput, just based on having faster drives available.  
> 
> I'd be willing to bet two things:  a) you couldn't meet their specs; and
> b) that you couldn't even come close to doing so at even twice same cost.

Of course, do they even meet their own specs?  My IDE drives run nowhere
close to the 33 or 66 megs they advertise.  I'd be shocked if ATA100 drives
run anywhere near 66mb/s either, but each hard drive has to crank 66mb/s
sustained to meet the Apple spec.
 
> To quote from the "storage" page:
> 
> 	Apple Drive Modules use 7200rpm ATA/100 hard disk drives. Each
> 	drive has an independent Ultra ATA/100 bus, an arrangement that
> 	allows maximum individual drive performance without choking the
> 	throughput of the other drives. The ATA drive subsystem has a
> 	high-bandwidth I/O bus that minimizes bottlenecks, even when all
> 	four drives are engaged at once. That's how Xserve can achieve a
> 	theoretical peak performance of up to 266 megabytes per second,
> 	compared to a 160MB/s theoretical performance with SCSI Ultra160
> 	disk drives - at a significantly lower cost, and while
> 	generating less heat than SCSI drives.
 
> In other words you'd need to add a pair of AIC-7892 chips or equivalent
> onboard, and put them on their own separate direct system controller
> attached PCI bus, to do what they're doing.

It would be better to find out what the machine can do, then meet that.
I suspect that a single U160 chanel running at full capacity is enough to
meet it, but maybe they really did come up with something that could come
close to what they advertised.

Of course, matching capacity using only 4 drives will still blow 2x the cost.

> I'm simply amazed that they managed to get hot-swap to work with ATA/100
> and SCA-II connectors (and I hope nobody ever tries to direct-plug any
> SCSI drive with an SCA-II connector into the damn thing! :-).

If you only have one drive per IDE chanel, then there is no reason that the
controller chip can't reset a chanel.  I believe 3ware cards support 
hotswapping.

-- 
Joshua D. Boyd