adding drives to 3B2

[Piercarlo Grandi]

In article <17482 at cisunx.UUCP> jcbst3 at unix.cis.pittsburgh.edu (James C. Benz) writes:
    I am considering adding some hard drives to our 3B2 system here (more correctly,
    replacing the internal 32MB drives with bigger ones)  and I'm having some 
    trouble getting the information I need to make a decision.
    
    HH1050	53MB	unformatted	rll recording	$500
    HH1060	80MB	unformatted	rll recording	$468
    HH1075	75MB	unformatted	mfm recording	$667
    HH1095	112MB	unformatted	rll recording	$800

    1) has anyone out there used one of these drives with a 3B2 and how hard is
    	it to do?

I haven't, but they are standard ST412/ST506, and I would be very surprised
to learn they do not work. Note that HH1075 is probably just HH1050, only
certified for RLL. Also, note the unformatted -- formatted it will tipically
be 25% less, i.e. 40MB, 60MB, 60MB, 70MB.

    2) what does rll,mfm mean?  Does it matter?

MFM is a recording encoding that is most common with ST412/ST506 interfaces;
RLL is another one that packs more bits per tracks than MFM, but requires
tighter tolerances on the disc unit. If you have a controller that only
supports MFM encoding, you do not need any disc certified for RLL.

    3) are there any other hard drives we might want to look at for under $1K?

I am looking at the same class of drives, for my AT clone. I will buy either
the Miniscribe 6085 (28 ms., 71 MB formatted, full height) that you can find
for about $600-650 from various mail orders, the Miniscribe 3085 (22 ms.,
71MB formatted, half height) that comes for around $700-750, the Micropolis
1325 (28 ms., 72MB formatted, full height) for about $600-650, and for
a similar price also the Seagate ST4096 (28 ms., 80MB formatted, full height).

Among these my favourite is the Miniscribe 3085 (half height and 22 ms is
worth the price difference to me, and as far as I know it is the ONLY half
height disk of that capacity with an ST406 interface), while I don't trust
the Seagate ST4096, as apparently the intense seeking of a multiuser UNIX
system is not well tolerated by it.

Unfortunately I have heard that Miniscribe is having serious problems. Too
bad, they manufacture a range of very good discs. I may buy a Micropolis
instead.
-- 
Piercarlo "Peter" Grandi            |  ARPA: pcg%cs.aber.ac.uk at nss.cs.ucl.ac.uk
Dept of CS, UCW Aberystwyth         |  UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK  |  INET: pcg at cs.aber.ac.uk