[Discuss] SSD drives vs. Mechanical drives

[richard.pieri at gmail.com (Richard Pieri)]

Bill Bogstad wrote:
> 1.  SSDs are constantly moving data around in order to do wear leveling.

Not constantly. SSD on-board controllers automatically perform garbage
collection when they're idle. Not when the systems are idle; when the
controllers are idle. Or they can be sent a trim command to initiate
garbage collection.

> 2. Not all SSDs have batteries/super capacitors to finish those
> activities if power is lost.

I'm unaware of any consumer-grade SSDs with batteries or supercaps.
That's typical of enterprise-grade devices but those tend to cost
substantially more than consumer kit.

SSD performance is largely dependent on massive DRAM caches on the
controllers. Seagate's super-fast Cheetah disks have 16MB DRAM caches;
the Samsung SSD you referenced previously has a 512MB DRAM cache. That's
where the performance comes from, and that's one place where data loss
is going to clobber you hard if the power fails.

There are other possible problems; I leave it to the reader to ask
Google about SSD power failures.

-- 
Rich P.