Need info about server-configurations

[Larry Beaulieu]

In article <5023 at brazos.Rice.edu>, dnlunx!odin!ben at relay.eu.net (Ben Lippolt) writes:
> My questions are:
>  - Which power should the server have?

If you're going to be stuck with using DEC, forget anything less than a
64xx (er, 6000 series 4xxx) or 5800 series (MIPs based) system.  A SCSI or
Q-bus based VAX just won't have the I/O horsepower required, never mind a
Massbus system, and the Q-bus on the 5400 is not a great performer, either
(3-5 MB/second). This gives you 7-36 MIPS to play with, depending upon the
number and type of CPU. 	

We used a 780 (configured for maximum I/O performance; 2 Unibus, 1 UDA50
per bus, 1 RA drive per controller) to service 5 standalone 3/60's
mounting the user directories only while waiting for our Sun server.  The
users were much happier after the 3/280 came in and we made the 3/60's
dataless.  

In general, your server should offer CPU performance comparable to that of
the clients.  Therefore, the VAX would be marginal, but the MIPS box would
be fine, as well as a Sparcserver 370/390 using SMD or IPI drives. ( but
do you want to back up on a cartridge drive on a 370?)

Noteworthy points: 

- With DEC, you are stuck with a single or twin (ASMP) CPU model, since
  Ultrix doesn't yet support SMP.  If you can get a MIPS based system, so
  much the better, @ 18 MIPS per CPU vs 7 for the VAX. 

- A BI bus is rated at 13.3 MB/sec, vs. the 40 MB/second for VME.  The DEC
  systems use an 80MB/second bus (XMI) to house the CPU's, with the BI bus
  used as an I/O bus.  You can get multiple BI buses on a system. The actual
  throughput on the VME bus for I/O on the higher end Suns is supposedly
  approximately 16 MB/second.

- Ultrix does not yet support HSC's to boost I/O throughput, so

- Beware of MIS types pushing for the VMS/Ultrix connection product from
  DEC. Everyone I've spoken to who as an opinion has generally been
  negative. 

- An 8000 series VAX cannot adequately support a bunch of DECstation
  3100's (per a senior engineer at Spitbrook); the DECstations demand too
  much from the poor beast. Given a DECstation 3100 approximates a
  Sparcstation 1 (in rough terms, no wars please) one could draw the same
  analogy using a Sparcstation. 

>  - In case of a DEC-server, which one would be sufficient?

As I imply above, a 5810 should be fine, expecially if equipped with
multiple BI buses (use multiple disk controllers spread out between the
buses). If you must have a VAX, then a 6420 (6000 model 420) would be
better.  See the next paragraph, though.

>  - Is it possible to boot SUNs from a non-SUN machine?

No.  You could, however, have a dual server configuration where the Sun's
boot off another Sun and mount the user directories (/usr/users, etc. off
the DEC server).  I suppose it would be possible to make it work, if you
wanted to spend the time and effort to do so, as well as write some
software.

>  - Which solution do YOU favor, a SparcServer-3X0 or a DEC fileserver?

1) The SparcServer can service all the needs for your Sparc and Motorola
   680x0 based Suns as it comes out of the box.  The same cannot be said for
   any of the DEC systems, although I suspect a high end DEC server could
   severely thump a SparcServer, for a given load. 

2) Do you really want to have a multi-vendor development environment when
   you don't have to?

In this case, I would go with the Sun.   

Larry Beaulieu 				...uunet!gca!beaulieu	
SMTS/Software Engineer
GCA Corporation, 			"Live to step, step to live..."	
Andover, MA