[svlug] Slides from the GoLUG meeting

[Ivan Sergio Borgonovo]

On 06/02/2016 09:56 AM, Rick Moen wrote:

> Slides from my talk are available directly from the front of
> http://www.svlug.org/ .

I admit that as soon as someone told me "things are changed, you don't 
have to bother anymore", being lazy, I bought it.

When I bought my first SSD I was concerned of loosing my data and I did 
some research and "tuned" my system for SSD. Now it seems that if you 
pick up the right model/brand even in the "consumer" space, all those 
concern are gone and there is no need for tuning.
The really worst thing that can happen is the manufacturer screwing 
their firmware with some exotic bug.

You can set the scheduler via udev

# set deadline scheduler for non-rotating disks
ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="0", 
ATTR{queue
/scheduler}="deadline"

# set cfq scheduler for rotating disks
ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="1", 
ATTR{queue
/scheduler}="cfq"

but that doesn't seem to be needed anymore.

Wearing SSD seems to be a non issue as well, for a "home" use so, moving 
/var or "things that change" including your /home is just going to slow 
down your system (and pretty much).

Samsung 850 PRO comes with a 10 years *limited* warranty that should say 
something (150TBW).
I don't know if 150TBW for a 1T SSD are enough for every application but 
they are far than enough for me.

If I had to be concerned of something I'd be concerned of the 
manufacturer firmware. Firmwares are reasonably complicated and offer a 
lot of "tuning" space and they are strictly dependent on the underlying 
solid state technology and there things don't seems to be settled.
Complicated moving things tend to be buggy.

So theoretically we should be near to forget everything about SSD tuning 
at higher layers, practically:

http://techreport.com/news/28473/some-samsung-ssds-may-suffer-from-a-buggy-trim-implementation

http://www.anandtech.com/show/8617/samsung-releases-firmware-update-to-fix-the-ssd-840-evo-read-performance-bug

...

and it is not just Samsung... it's just that they have a large slice of 
the market and their mistakes resonate through the net.

Conclusion:
- if you're a "home" user I wouldn't tune anything, leave everything on 
SSD unless you really have to store a lot of data and cost/GB is a concern
- watch out for firmware bugs

-- 
Ivan Sergio Borgonovo
http://www.webthatworks.it