A5000: no NVRAM?

[Charles Seeger]

+------ Andy Wilcox wrote (Thu, 19-Mar-98, 20:19 -0500):
| 
| On a related note, a colleague and friend probably on this list, Chuck
| Seeger, once remarked that he'd rather have the 1G of cache on a
| hardware Raid-5 box closer to the CPU than at the other end of a scsi
| chain.

Let me clarify slightly...  RAID-5 is the case where RAM in the controller
is most useful, especially if your performance critical workload includes
a significant amount of non-full-stripe writes.  For RAID-0+1, I do think
the memory is generally more useful on a fast memory bus rather than a
slow I/O bus.

However, non-volatility can be another concern.  AFAIR, Sun and Legato
never had PrestoServe working with raw disk partitions (or was it that
it was never officially supported?).  That then brings up the question
as to whether it would work with other file systems, e.g. VxFS.

There might be some interesting things to be done with a general NVRAM
capacity.  Someone from, I think, Berkeley published a paper four of
five years ago about increased reliablity and fast restarts.  Alas,
I don't have a reference handy.

Best Regards,
Chuck