ESDI vs SCSI

[Paul A Vixie]

[Steven List]
# I'm trying to decide between ESDI and SCSI.  I've heard a little of this
# and a little of that without hearing anything that would really help me
# make a decision.  I've been considering the DPT caching ESDI controller.
# Needless to say, as soon as I said so, someone told me I should REALLY
# be considering SCSI.  Can anyone out there educate me a bit?

Oboy.  This is going to be a major flame fest, methinks.  It always is.

I have been extremely satisfied with ESDI.  The drive does bad-sector
maintainance -- allocating spares, keeping track of the bad ones, etc.
With a 1:1 track-buffering DMA controller and the 386/ix file system
implementation (SysV compatible media but better code in the kernel),
I think I'm bus-speed limited.  Since ESDI has good system management
goodies and is fast enough to not be the weak link in the system, it's
been my clear choice.  Some of the nicer CDC drives are available with
an ESDI interface, too.

SCSI, on the other hand, is potentially faster in synchronous mode, now
that decent SCSI controller chips are getting common.  And ALL of CDC's
big/fast drives are made available in SCSI before any other interface;
with SCSI becoming more common, the prices of SCSI drives are a little
bit more competitive than the prices of ESDI drives.  I see no reason NOT
to go with SCSI at this point, but it isn't enough better to get me to
switch on future systems -- I'm too comfortable with the tools at hand.
Eventually, the variance will get decisive.

If you aren't committed already, and you can find a dealer or a consultant
who will guarantee that the SCSI approach will work, jump in.
--
Paul Vixie
Work:    vixie at decwrl.dec.com    decwrl!vixie    +1 415 853 6600
Play:    paul at vixie.sf.ca.us     vixie!paul      +1 415 864 7013