[Info-vax] Databases versus RMS

[Ken Fairfield]

On Thursday, April 19, 2012 11:18:01 PM UTC-7, Jan-Erik Soderholm wrote:
[...]

> The DECs SSD in SSB's (StorageWorks disks) was RAM based as far as I know.
> That is, did not retain data at power loss. Was often used as one part
> of a schadow-set so that all reads was doen from the RAM disks and all
> writes went to both (and thus stored permanently).

The first Intel fab I worked at was using DEC SSD's for the "hot"
database files.  This was VAXcluster (7800's IIRC).  I'm pretty
sure the SSD's were in SSB's.  I *know* that these SSD's had
rotating disks in the same package (SSB) for non-volatile storage.
I don't recall for sure, but I *think* they had (small?) batteries 
as well so the memory could be written to the disks in the event of
a power failure.

What I found interesting is that, by the time I got there, these
SSD's were suffering a fairly high failure rate.  And it was 
universally the rotating disks that were failing. ;-p  OTOH, by
the time they were failing, you couldn't buy such things anymore
(from DEC/Compaq).

We were able to get as good performance for the database over FC/HSG
with Host-Based RAID striping (and a few other configuration tricks)
on the Alphas that replaced the VAXes, so we didn't need SSD's anymore.

[...]

    -Ken