scsi disk (IDT)

[Larry McVoy]

In article <574 at n8emr.UUCP> gws at n8emr.UUCP (Gary Sanders (n8emr)) writes:
>I talked with IDT again today and got some more info on the scsi
>interface for the 7300/3b1.. 
>
>Looks like this will be an easy way to increase your disk space..
>scsi board, scsi to 506 interface and a bunch of cheap 506 10/20/40mb disk.

I can suggest what I think is a *much* better idea: buy a bernoulli box.
They were expensive ($1500?) a couple of years ago, but I'll bet they're
reasonable by now.  They come in 10, 10+10, 20, 20+20, 10+HD, 20+HD, and
maybe other configurations as well.  They're basically an 8inch floppy that
holds 10|20 megabytes, spin about the same speed as a disk, have about the
same xfer/access time.  I've used them on an AT running QNX (a small
msg passing OS that has some unix feel to it) and I've run off of the 
bernoulli (i.e., root mounted on /dev/bernoulli0).  The only problem is 
that they don't spin the disk all the time, so you suffer a delay if the
machine has been idle (disk wise) for 30-120 secs.  You can easily get
around this by writing a disk daemon that touchs the disk every 30 secs.
bdflush will do that for you, now that I think about it.  Disks cost about
$10 each....  Think about it - you can mount /usr/news on one and backup
to the other.  Limitless random access disk space....  And if you want to
use them like tapes, hey, no problem...

If they do come out with a scsi board and specs, I'll buy a bernoulli and
write the driver (I have an old SysIII based scsi driver for the 
bernoulli somewhere).
-- 
Larry McVoy	lm at arizona.edu or ...!{uwvax,sun}!arizona.edu!lm