CD-ROM from SCO unlikely
shoppa at alph02.triumf.ca
Sat Feb 28 16:07:21 AEST 1998
> > Incidentally, a couple of weeks ago I made a nice bootable Iomega ZIP
> > cartridge with the current 2.11 generic kernel and everything in /usr. It all
> > barely fits in the 100 Mbytes (well, 3*65536*512 bytes) available, and
> How "speedy" is a ZIP drive?
On my Andromeda SCDC, the effective transfer rate to the Q-bus is just
under a megabyte per second. In other words: damn fast. (Fast
7200 RPM SCSI-II hard drives will get 1.5-2 Mbyte second). Booting
from ZIP is far, far faster than booting from a RD54. I posted some
benchmarks to vmsnet.pdp-11 two months or so ago.
> I keep threatening to get a JAZ drive
> for my 11 - they're nice. I don't like the DB25 style of cable
> that the normal external ZIP drive uses so I'd have to find one of the
> rare internal ZIP drives and stuff it into a traditional shoebox.
That aren't all that rare. You just have to go someplace other than
Fry's, that's all :-).
> > -11's with SCSI host adapters than the traditional tape distribution.
> Tape's good for backups though, so when I don't feel like putting up
> with the racket of the 9-track I just cable up the 4mm drive to
> the 11/73. Alas, the QIC style of drives don't work, at least not
> with the Emulex UC08. For a brief moment the Seagate Tapestore 8000
> appeared to work but then the whole system/controller hung (I suspect
> the UC08 doesn't know how to deal with more modern tape drives).
> The older QIC (Wangtek-5150ES) doesn't work at all - the UC08 barfs
> at drives that don't do variable record mode. Do the CMD adaptors
> do any better with "PC" style SCSI tape devices?
The problem is that most QIC devices are commonly operated in fixed-size-
block mode, something that TMSCP doesn't really grok well unless its
hidden under a layer that hides this and allows for variable-sized
"virtual" blocks. (Your TK25 takes care of all of this for you
> > have - the CMD CQD440, the Emulex UC08, and the Andromeda SCDC - bootable
> > CD-ROM distributions are entirely possible. I'm not sure if 2.11BSD will
> Uh, 2.11 doesn't know how to deal with 2048 byte sectors or the
> ISO9660 filesystem.
That's OK. The MSCP controllers make each 2048 byte sector look like
4 512-byte blocks. And you don't need to lay down a ISO9660 filesystem;
if you throw away the idiotic software that comes with the PC-clone
CD-ROM writers, you can put any filesystem you like down. I've
built bootable RT-11 CD-ROM's this way.
> > boot from a read-only device - Steven, have you tried this?
> It'll panic. For a couple reasons: pipes are implemented via
> the filesystem rather than sockets so anything involving pipes
> needs a rw filesystem. And a swap area is needed. If there's
> memory available there won't be any actual swapping going on but
> argument gathering, etc during an 'exec' can use a small amount of
> swap space. It might be possible to use a 'ram' disk
RT-11 also wants a writable swap file, and this is indeed provided by
using a RAM disk (i.e. VM:).
> but it's not
> clear to me it'd be worth the trouble.
It depends on how convenient you find installation from CD-ROM :-). I find
the bootable ZIP disk very convenient for "recovery media", and they're
a whole lot easier to fit in my shirt pocket than a RL02 cart!
Tim. (shoppa at triumf.ca)
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