🚀 go-pugleaf

In article <372F7F44.13680993@lily.aerc.colostate.edu>,
  Chris Carlson <chris@lily.aerc.colostate.edu> wrote:
> Adam Carheden wrote:
> > - Hard Disks
> >   WDE9100 (Western Digital) $820
> >   9.1 GB
> >   7200 RMP
> >   7.9 ms Average Seek time
> >   4.17 ms Average Latency
> >   Ultra Fast/Ultra Fast Wide/SCA-2 interface
> >
> >   ST19171 (Seagate) $230
> >   9.1 GB
> >   7200 RMP
> >   8.0/9.5 ms Average Seek Time
> >   4.17 ms Average Latency
> >   Ultra SCSI (8- and 16-bit, SCA) interface
> >
> >   Why does a .1 to 1.6 ms difference in seek time justify a $590 price
> >   difference.  What did I forget to look at?  And what about the
> >   differnce in interfaces; is this two ways of saying the same thing?
>
> The difference is that the Seagate is utlra scsi and the Western
> Digital is probably ultra wide and scsi-2. Don't quote me on this,
> but I think that ultra is 20 MB/s, ultra wide is 40 MB/s, and ultra
> wide scsi-2 is 80 MB/s transfer rate. The ultra has a 50-pin scsi
> connector and the ultra wide has a 68-pin scsi connector. I'm not
> sure what type of pin connector the scsi-2 has. If you buy a new
> scsi hard drive, make sure it will fit on the scsi adapter you have.
> I know Adaptec make scsi cards with both 50 and 68 pin connections.

This is bogus and mis-sleading.

Both stated with SCA connectors, which are wide. His seagate spec's say
8-bit (narrow) and 16-bit (wide) ... and both say Ultra, AKA Fast-20,
which uses a 20MHz synchrous data clock, which for 8-bit is 20MByte/sec
and for 16-bit (wide) is 40MByte/sec.

Not mentioned is Ultra-2 which is the new high speed and low voltage
scsi standard, which is most often seen in the LVD (low voltage differential)
form. Special cable and terminators are required, LVD controllers generally
only support LVD drives. I've been using them in my servers for a year - very
fast.

SCA connectors are designed for RAID gear, and are not the normal 50/68 pin
scsi connectors most people have seen/used. An SCA adapter is required on
the drive to use normal SCSI cables and controllers.

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