At 23:48 -0400 09/01/2005, [EMAIL PROTECTED] wrote:
Hi,
I'm considering the purchase of an Ultra SCSI drive (external) and
controller card to use w/ my S900. Does anyone have a particular combination
that they're happy w/? From the reading I've done, Seagate seems to be
highly favored for a drive and Adaptech for a card. Which is the fastest
SCSI format that will give me performance I can realize w/ an S900? Can I
consider Ultra 2 Wide or even Ultra 160? My configuration is as follows:
Sonnet G4 450MHz processor
Nothing in slot A (am planning to put Ultra SCSI card here)
SIIG UltraATA 133 controller in slot B
Video card in slot C
Nothing in slots D and E
Belkin USB 2 port card in slot F
120 GB WD EIDE Internal HD
Two 2GB Internal SCSI HDs
1 GB RAM
For compatibility the Adaptec 2940UW may be your best bet. However,
I do not believe that it is supported under OSX. IIRC, it will work
under OSX but one cannot boot from drives attached to it. You did
not mention if OSX compatibility is a consideration.
The advantage of going to Ultra2Wide, AKA LVD, SCSI is that it is
more tolerant of longer cable lengths. If you are using just one
external drive, this is unlikely to matter, but if you connect more
devices it can be important. The cable length limitation under plain
UW SCSI is fairly limiting.
The disadvantage of U2W is that it requires somewhat more expensive
cables, but they've become the norm now, so I don't think you'd have
any trouble finding affordable ones.
You can do Ultra160 but there probably isn't much point to it.
Ultra160 is theoretically 160 MB/s maximum transfer. The maximum
theoretical transfer rate of the S900 PCI slots (and all original
PCI) is 33 MHz X 4 bytes = 132 MB/s. Real PCI performance will be
something less than 100 MB/s. There's always overhead on a bus.
Still, if the U160 card isn't much more expensive than a U2W card,
why not get it?
Additionally, real world hard drives don't deliver data that fast
anyway. Unless you're going to set up a performance enhancing RAID,
I don't think that real performance of hard drives is much better
than 60 MB/s yet, though I may be out of date on that. That's how
fast a hard drive can actually get data off of its spinning platters
and deliver it to the electronics.
Older hard drives are slower still. Go back just a few years and top
performance of hard drives was only 20 MB/s regardless of how fast
the electronic interface was. Go back to the original Barracudas
(ST32550N or ST32550W) and the real performance was 6 MB/s. The
ST32550W was Fast & Wide SCSI which can transfer up to 20 MB/s, but
the hard drive could only deliver 6 MB/s to that fast interface.
So if you buy a SCSI drive model that was released a few years ago,
expect much slower performance (regardless of the electronic
interface, flavor of SCSI) than with an up-to-the-minute SCSI drive
that was just released in the last few months. Of course, price will
reflect this difference.
If I were buying a new SCSI card at this time, I would look at the
Acard SCSI cards. Acard makes the most compatible UltraATA adapters
for our machines. If they put the same quality into their SCSI
cards, I'd expect them to be very good, but I've never tried one
myself. You can look at all of Acard's products on their site
<http://www.acard.com> and their US distributers are
<http://www.microlandusa.com> and <http://www.getlaptop.com/> .
Jeff Walther
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