[OPEN-ILS-GENERAL] Solid State Drive

[John Morris]

On Wed, 2014-07-23 at 16:20 +0000, Sue Ciani wrote:
> Has anyone implemented solid state drives on their database servers?  If so, what was your experience? Did it increase response time?  Did you put them only on your database server?

We implemented on SSD from the start in March 2011 for both the frontend
and backend.  We have both as VMs rotating across three physical hosts
(one is always cold unless we are testing a new Evergreen version by
running both front and back on the spare) which spreads the wear a bit.
But while I was a bit worried about the stories we all hear about SSD
wear, not a problem.  The lowest number I'm seeing right now for Media
Wearout Indicator is 97.  The flash will almost certainly outlast the
servers they are mounted in.

Now for the downside.  Don't know if it is something in the VMs
(although I have even tried migrating a front to bare metal as a test
and it didn't help) Perhaps it is something inherent in the multiple
layers of abstraction PINES needed to scale beyond what a single server
could do back at the turn of the century, general lack of performance
inherent in XUL + Javascript on the Staff Client or what but I have
never been impressed by EG performance.  Even on an unloaded network
(after close) requests involving large numbers of items take far longer
than they 'should.'  Direct queries with PGAdmin or Perl scripts are
plenty fast since the whole DB fits in ram.  So don't go buying a stack
of SSDs hoping to see a big performance gain, rotation speed apparently
isn't the bottleneck.
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