🚀 go-pugleaf

On Tue, 11 Aug 2009 23:30:35 -0700 (PDT), Penang
<kalambong@gmail.com> wrote:

>Please pardon me if this topic has been discussed before, but as far
>as I know about the Flash memory, they have a relatively low limit on
>re-write, as compared to hard disk
>
>In situation where database use in concern, read and write operation
>takes place very often
>
>I know that there are pros and cons in this issue, but basically my
>question is this --- How reliable is SSD?

We cannot reasonably generalize this, it depends on your
specific database use, how often and the amount it would
write/rewrite data versus the total capacity of the SSD.

Consider that if the database is 4GB and you have an 8GB
HDD, so it has 4GB free space, the wear-leveling feature of
an SSD would write 7X more often to each free area than if
you had 4GB database and a 32GB SSD (28GB free space).

That 7X could be very significant, suppose the SSD would
last 2 years if 8GB total or 14 years as 32GB total.

I haven't yet mentioned MLC vs SLC flash chips, chosing the
latter typically extends write cycles by roughly 10X.  Now
in the above context consider a lifespan of 2 years or 10 x
14 = 140 years.

When all is said and done, if you pick the right SSD for the
job including it having excess capacity, it is far more
reliable than a mechanical hard drive is.  MUCH MUCH more
reliable, nobody in their right mind would use a mechanical
HDD for more than a single-digit # of years for any
important database use, that single-digit number of years
closer to 0 than to 9.