Asynchronous Parity on Sun 4/3xx and 4/280 upgrade

[Ken Mandelberg]

I notice that Sun has a promotion that packages the sale of new Sun 4/280s
with an "upgrade" to the Sun 4/3xx CPU and memory.  There is a warning in
the description of this program that this ends up trading the 4/280s ECC
memory for the 4/3xx asynch parity memory, which is less reliable and may
not be suitable for critical applications. The examples given of
"critical" are financial applications, or fileservice for a large number
of workstations.

In case someone at Sun who is familiar with this issues is listening my
questions are:

1) How serious an issue is this? Is there some way to quantify it?  If the
"mean time between crashes" goes down 5% without ECC, it is not too bad.
If it goes down 50% it is.

2) Does that parity issue effect an upgraded 4/280 any differently than it
does a brand new 4/390? The 390 is advertised as being Sun's best
fileserver for a large number of workstations.

Though not related to the memory issue another related question to the
upgrade is:

3) Other than the obvious issue of the IPI disks and new front loading
tape drive, does an upgraded 4/280 suffer any other deficits relative to a
4/390? For example, does the backplane on a 4/280 preclude some additional
upgrade that a 4/390 does not?

Ken Mandelberg      | km at mathcs.emory.edu          PREFERRED
Emory University    | {decvax,gatech}!emory!km     UUCP 
Dept of Math and CS | km at emory.bitnet              NON-DOMAIN BITNET  
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