[olug] SSD write durability in production use

[Will Langford]

On Mon, Oct 13, 2008 at 8:20 PM, John Vogel <jpvogel1 at gmail.com> wrote:

> Actually, there is a limit on the number of writes per memory address of
> about 10,000.  So, if the DB is *read only* accessible it would last 6
> years
> or so, but if a lot of data is modified and stored each day you could end
> up
> having to replace it in a few weeks.
>
> So SSD are best used to hold data that doesn't change often but needs fast
> access like library files and the boot image.
>


A few years ago that would probably be true, but looking at current SSD's,
write cycles appear to be typically 100,000 write cycles.  They've added a
zero :).  The key, when attempting to pick the drive with higher write
durability is to skip the bogus MTBF number they offer and dig for the write
cycle durability.

Lastly, the assumption on the extra zero is this isn't just an offset to
reflect wear leveling (ie: we're assuming it's not a pure marketing number
ala AMD PR ratings).

A 100,000 write cycle sounds awefully tiny, but with wear leveling and the
1MB/sec chart at 50% wear leveling ability (below industry 'standard'), you
end up with 4 years of life out of it according to the chart.

-Will


-Will