[Info-vax] Databases versus RMS

[Paul Sture]

On Thu, 19 Apr 2012 05:53:40 -0700, abrsvc wrote:

> On Thursday, April 19, 2012 8:37:52 AM UTC-4, Paul Sture wrote:
>> On Wed, 18 Apr 2012 18:08:52 +0200, Dirk Munk wrote:
>> 
>> > Many hours, sometimes even a few days. Usually the disks are not
>> > powered by the batteries, only the RAM memory of the cache.
>> 
>> I was given a demo of a RAM disk with real disk backup in the early
>> 1990s.  The battery in that was supposed to last long enough to copy
>> the RAM contents to the physical disk in the event of a power fail.
>> 
>> I never saw any of these deployed anywhere though.  I wouldn't be
>> surprised if they were too expensive.
>> 
> 
> Digital did work on SSD devices (Solid State Disk).  I recall working on
> the performance testing of these.  The prototype for testing simulated
> an RA81 disk and actually was breadboarded using the front panel of the
> disk.  I recall laughing at the drive's requirement to "spin up" before
> it was available.

I might have mis-remembered but I was thinking that on power up the 
device read the disk contents into memory, and on power off or power loss 
it spun up the disk and wrote to it.  I think the model I saw was a 
Hitachi product, so may have done things differently from the DEC one.


-- 
Paul Sture