[Nottingham] SSD and Linux

[Andy Smith]

Hi Albert,

On Thu, Sep 10, 2015 at 11:00:46PM +0100, Albert wrote:
> Anyone got any recommendations for a SSD?

Buying new I don't think you can go very wrong with Intel or
Samsung. You probably wouldn't have issues with any of the other big
name brands either like Crucial, Kingston or OCZ.

Once you find one you like the price of, just do a search for
reviews. You're bound to find a storage review or anandtech or
whatever article that features it in a lineup.

> I don't mind it being low capacity or even second hand

As others have said, I would not buy an SSD second hand right now as
in my opinion the technology isn't mature enough for a healthy
second hand market to make sense.

Great advances have been made in endurance and capacity in a fairly
short period of time, so not only would second hand not be so
cost-effective but could even be a false economy if the device had
been heavily used.

Any decent SSD can tell you its usage figures in the SMART output,
so if considering buying hand make sure to ask for the output of
"smartctl -a" and compare it to the data sheet's endurance promises.

Newer ones will even tell you their forecast for endurance:

$ sudo ./isdct show -d EnduranceAnalyzer -intelssd
- IntelSSD BTHC511XXXXXXP6PGN -
EnduranceAnalyzer: 68.95 Years

- IntelSSD BTHC511XXXXXXP6PGN -
EnduranceAnalyzer: 74.79 Years

> must be reliable and cool running.

Cool running won't be an issue: SSDs draw far less power than HDDs.
Reliable, well, anything can break. Have backups and use more than
one device if availability would be an issue!

These days the only real tweaks that might be a factor are:

- Ensuring correct partition alignment.

- The IO scheduler (generally get better performance out of
  "deadline" or "noop" rather than the default "cfq").

- How you approach TRIM (have the filesystem do it, or do it
  "offline" with fstrim command).

Here's some more info on those topics that is generally applicable
to all Linux distributions:

    https://wiki.archlinux.org/index.php/Solid_State_Drives

Even so, I would say that large sections of the above document are
archaic. Particularly I would ignore the entire section on
minimizing disk writes.

It's worth learning about how to use tools like "fio" in order to
check that you're getting performance figures that are somewhere
approaching what is promised.

Cheers,
Andy

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