[Discuss] ssd's in linux

[blu at nedharvey.com (Edward Ned Harvey (blu))]

> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
> bounces+blu=nedharvey.com at blu.org] On Behalf Of Stephen Adler
> 
> I'm thinking of upgrading my linux system by adding an SSD drive to use
> as my system disk. Has anyone done this? Any pros and cons regarings
> using SSD's? I'm more intrested in the cons. I'm worried about the life
> expectancy since there is a limited number of writes one can do to the
> NAND memory. Do I need to setup a raid array to ensure the SSD contents
> are correct?

That is legend.   ...   Meaning ...  something that once was true which is no longer true ...  Actually it's still true, but now it's irrelevant in all but the cheapest junkiest devices.  And it may not even be a problem in the cheapest junkiest devices.  It's very likely that all 2.5" SSD's have intelligent controllers in them...  The same is not true for USB and SDCard devices, etc.

The solution to NAND lifetime was wear leveling (obviousl requires an intelligent controller).  Every time you write to a block of the SSD, the SSD internally maintains a mapping table and remaps everything around physically.  You think you keep writing to block 0 or whatever, and internally the SSD spreads it out across all the blocks.

There was also a problem with garbage collection, which is really a non-issue anymore, thanks to intelligent controllers.

Performance on day 1 will be the greatest.  It will degrade over time, but it will take a fair while before you could notice or measure the difference.  And even after a couple years of continuous usage, it'll still be way faster than the HDD.

When you upgrade, you tend not to notice.  But if you ever need to downgrade, you suddenly realize you've become a snob, because how can the rest of the schmoes in the world live with this crap.    ;-)