Re: [gentoo-user] SSD partitioning and migration

[Paul Hartman]

On Fri, Jul 19, 2013 at 1:45 PM, Mick <michaelkintzios@×××××.com> wrote:
> On Friday 19 Jul 2013 17:43:39 Dale wrote:
>> luis jure wrote:
>> > on 2013-07-19 at 01:56 Dale wrote:
>> >> Do you really want to put /home on a SSD?
>> >
>> > well, not actually the whole /home, the SSD is too small for that. i'm
>> > not sure yet, i might keep /home on a HDD and mount the partition on the
>> > SSD as a directory under /home for some special uses. or the other way
>> > around...
>>
>> Size was one issue I thought of but I was more concerned with the wear
>> and tear part but that was explained by others.  It seems that is not as
>> much a issue any more.
>>
>> At one time, I had a /data directory.  I stored large stuff there:
>> camera pics, videos, audio stuff and such.  If you put /home on SSD, you
>> could always put the larger stuff on another mount point.  One thing
>> about Linux, you can mount stuff wherever you want.
>>
>> Post back how it works out and any speed improvements you see.  I'm
>> really curious since I would like to get one that is at least big enough
>> for the OS itself.  My /home is over 1Tb, that is Tb too. I'm not buying
>> one big enough for all that.  lol
>>
>> Dale
>>
>> :-)  :-)
>
> I have a MUCH smaller /home than Dale and on a new box I was thinking of
> having it on a HDD, along with all things portage related.  I typically resync
> 3 -4 times a week but I am not sure how much erase/write cycles this
> represents.  Also, /home is written all the time with mail and various
> application profile folders, browser cache and what have you.  That's why I
> was thinking that /usr/portage, /var/tmp/portage, /var/log, /home and /swap
> were candidates for HDD.

/usr/portage is one of the things that benefits the most from being on
a SSD, thousands of tiny files scattered all over the place. It really
is a tremendous difference compared to running portage on a HDD.

> I guess the rest under / does not change that often and a weekly or even
> monthly back up would be all that is necessary to facilitate recovery when the
> SSD dies on me.
>
> Am I being too cautious with current technology SSDs?

I think you are. Unless you are moving massive terabytes of data
across your drive on a constant basis I would not worry about regular
everyday write activity being a problem. I think the SSD is more
likely to die due to electrical shock or surge than by normal wear and
tear. Of course backups are always a good idea, no matter what. :)

Old SSDs that did not support TRIM would suffer write amplification
after a certain amount of data had been written to them, but any
modern SSD and modern OS will keep it nice and tidy.

> BTW, unless anyone advises differently, I was thinking of buying a SanDisk
> Extreme II, SATA III, 2.5" 240GB SSD.  I read that its SLC cache improves
> speed and reliability, but I don't know if true.

My personal experience is with these:

Samsung 830, 128GB
Samsung 840, 250GB
Intel 330, 180GB
Sandisk Extreme, 120GB
Sandisk Extreme, 240GB

(note mine are the older Extreme, not the new Extreme II's that you're
looking at)

The Samsung 830 and Intel 330 are the winners, they consistently had
the best random read/write performance in my testing, as well as
intangible "feeling" of responsiveness.

The Samsung 840 had lower write speeds (because it is TLC).

The Sandisk Extreme had a bit worse random I/O performance than the
leaders, but still not bad. The worst part about the Sandisks was that
it took them forever to release a firmware upgrade. They used the
infamous buggy Sandforce firmware, which every other SSD maker
released fixes for, but it took Sandisk what seemed like an eternity
to finally make it available.