[arch-general] ssd

[Leonidas Spyropoulos]

On 31 Oct 2012 00:29, "Juan Diego Tascón" <juantascon at gmail.com> wrote:
>
> On Tue, Oct 30, 2012 at 6:32 PM, André Prata <bugflux at gmail.com> wrote:
>
> > On Tue, Oct 30, 2012 at 10:52 PM, Gaetan Bisson <bisson at archlinux.org
> > >wrote:
> >
> > > [2012-10-29 21:58:01 -0500] Juan Diego Tascón:
> > > > I just got a new laptop with a 25Gb ssd and I was wondering which
would
> > > be
> > > > best if putting my home directory (minus music and videos) there or
and
> > > > arch install (minus pacman pkg cache). I read the ssd related
article
> > in
> > > > the wiki and even though it mentions some optimizations and
> > > considerations
> > > > it doesn't mention anything regarding this issue.
> > >
> > > With a high-quality SSD you do not really need to do anything.
> > >
> > > With a generic SSD, you should reduce the number of writes or spread
> > > them out evenly on all sectors. The latter can be achieved by using
file
> > > systems such as nilfs2. The former can be achieved by disabling system
> > > logging or making /var/log a tmpfs, and more generally by controlling
> > > write-hogs (think of XDG_CACHE_HOME, ~/.mozilla, etc.).
> > >
> > > But of course I cannot tell you as much as all the information many
> > > people have put on the Internet over time on that topic.
> > >
> > > --
> > > Gaetan
> > >
> >
> > I think the question is not as how to prolong the life of the disk, but
> > rather how to take advantage of such a small space with high throughput.
> >
> > Well, I guess that it's really hard to tell if you would benefit more
from
> > having your system or your user files in the SSD, if there is no space
for
> > both. In case of lodging the system there, you would benefit from faster
> > boot times, and some program calls. However, if you have a large memory
> > system, it will account less and less towards greater uptimes. If that
is
> > the case, your personal files would be a better fit.
> >
> > One third option, although I'm not sure of the reliability or of the raw
> > efficiency increase, would be to use the 25GB as a cache for everything
> > else, with gimmicks such as flashcache [1] or bcache [2].
> >
> > Or just google something like "SSD as a cache".
> >
> > [1] https://github.com/facebook/flashcache
> > [2] http://lwn.net/Articles/458417/
> >
> >
> > André Prata
> > http://about.me/andreprata
>
>
> Yes my question was more oriented towards the kind of answer you just gave
> me. To conclude I think I'll relocate my home directory to the ssd.

It's according to what usage you do to the system. My choice is making it
root except home, opt, and any cache, logging directory target to improve
the boot times. If on the other hand you rarely restart (using suspend or
not turning off PC) it's no use. Another factor would be power consumption,
as if you put all your frequently used files in ssd, your HDD would spin
down and save some watt (good for battery powered machines).

>
> One more question regarding the first answer: how can I tell if my ssd is
> high quality? are there any tests? or maybe a references-features list? or
> maybe some utility to fetch ssd info?
>
> Thanks to both of you

As others said also no test available but you can judge it by the price. If
you want to drill down to the problem, it's what kind of NAND the ssd is
using and the controller.