Experiences with 4D/2xx as timesharing systems?

[Rayan Zachariassen]

Whether in the short or long term, we are looking at the high-end SGI
boxes as compute servers and timesharing boxes.  In this context we are
totally uninterested in their graphics aspects.  I'd like to hear from
sites that are already doing this, if any, with any comments about this
kind of use of the SGI boxes.  I'm especially interested in comparisons
with other systems prior to purchase, and differences between expectations
and reality after you got the box in.  I gather these things have just
started shipping so the field is probably still meagre...

In order to get technical details out of the local salescritter we have
to ask specific questions, so I'd also like some general answers to the
following to get us going:

Our major worry (in the fine SGI tradition...) is with the software, in
particular we consider any System V based box to start out with a negative
(this is our reality not our religion).  We understand SGI is committed to SV.
Does this mean they will track AT&T SV releases directly, or that whatever
SV-based OS that MIPS comes up with will shortly appear on the 4Ds?

The filesystem is a worry.  We're happy it isn't SV but unhappy at the
apparent gratuitous incompatibility with the BSD F^nS.  Our tools are
unlikely to work, right?  It also seems like a less robust design.  Will it
go away in favour of something else that is largely compatible with
F^nS ((Fat)Fast File System)?  I note that MIPS ships FFS with their
rice-computer OS, how come SGI seems to be waiting for SVR4 to do the same?

During testing on the personal iris, some anomalies showed up that could
be explained by the scheduler or VM being tuned for a single-user workstation
environment.  For example running a certain (non-graphics) program would
cause lost ether packets and horrible response time on the iris, but the
same program is apparently wellbehaved on other machines.  Similarly, logging
out of the PI causes lost packets.  Anyone experienced similar anomalies
on the 4D/2xx?  Anyone using them for timesharing?

How does the fine-grained multiprocessing support (threads libraries, compiler
support etc.) differ qualitatively from other implementations (MachOS,
Sequent, Encore, Sun)?

Can one use a 4D to serve root and swap for a SunOS 4.0 workstation?

How is the hardware reliability on the 4Ds?

Any other pertinent comments from customers are welcome.  The kind of
configuration that is of interest is a 4D/240S with minimal extra stuff
(small SCSI, cartridge), to which we'll add the storage subsystem w/ a
few gigs of disk.  Users would have access via the ether.  In the
timesharing application we would want to potentially support at least
twice the work our Sun4/280Ss are being asked to do (which is 30 users
+ 30 workstations, mostly light activity but occasional developers and
long-running and/or large jobs) which it does well when it works.

Please REPLY BY MAIL!  I will summarize if interesting info appears.

Thanks,

rayan

AI/NA/Theory, DCS, U of Toronto