On Wed, 21 Apr 2010 18:40:10 +0200 Jurjen Oskam <jur...@stupendous.org>
wrote:
> On Tue, Apr 20, 2010 at 11:03:30PM -0700, J.C. Roberts wrote:
>
> > degrade. You might be better off in the long run using multiple
> > rotating disks that are half as fast, and half the price, but won't
> > degrade.
>
> It's my understanding that if you have a decent SSD, write response
> times can (under some workloads) degrade but never below the
> performance of even a very fast rotating disk.
>
> So, i've stopped worrying about things like TRIM and trying to avoid
> writes. I'll align my partitions, but apart from that I just enjoy the
> extremely low read response times, and my almost-always-quite-low
> write response times. :)
I agree. If your application does not require pushing things to their
limits, TRIM and degradation can be a non-issue.
When you have the budget to over-allocate with SSD's to exceed your
requirements (e.g. a plan to compensate for increased demand as well as
degradation over time), then they are an excellent choice. The problems
only arise when you don't have the budget, don't understand your
workload, don't do adequate testing, and don't plan for the eventual
degradation. Since all of these issues except degradation also effect
rotating storage, it's mostly a planing problem where SSD's just add
other variables to the analysis.
The trouble is SSD vendors are not particularly forthcoming about the
limitations, so they are not well understood by integrators and this
can result in poor planing.
jcr
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