Re: Options for SSD - autodefrag etc?

[Martin Steigerwald <Martin@lichtvoll.de>]

Am Samstag, 25. Januar 2014, 15:33:08 schrieb Imran Geriskovan:
> Every write on a SSD block reduces its data retension capability.
> 
> No concrete figures but it is assumed to be
> - 10 years for new devices
> - 1 year at rated usage. (There are much lower figures around)

Where do you have these figures from?

For the Intel SSD 320 in this ThinkPad T520 I read about a minimal usable live 
of 5 years with 20 GB host writes each day in the tech specs. Thats 7300 GB a 
year or 7,3 TB. I assume metric system here.

According to smartctl it has written

241 Host_Writes_32MiB       0x0032   100   100   000    Old_age   Always       
-       360158

360158 * 32 MiB (hmmm, now according to smartctl output this is MiB) which 
gives almost 11 TiB (10,99).

The SSD is over 2,5 years old. Thats less than 5 TiB a year.

So that would lay within the range you say. Although the Intel SSD 320 isn´t 
basically a new device in my eyes.


Thats with KDE session with Akonadi and desktop search, sometimes even two KDE 
sessions and a load of applications running at times.


Anyway that SSDs still thinks it is well *new*:

233 Media_Wearout_Indicator 0x0032   100   100   000    Old_age   Always       
-       0


Thats the same media wearout indicator (which takes into account the amount of 
Erase cycles according to Intel docs) it had at the first day I used it.


So I am basically not concerned.


While autodefrag mal cause additional writes… that would not even be the main 
reason for me not to use it at the moment. I am just not convinced that it 
gives any noticable benefit. And given that… of course it doesn´t make sense to 
me to have it cause additional writes to the SSD.

But I am not using it due to avoiding those additional writes in the first 
place.


My most important recommendation regarding SSDs still is: Keep some space 
free. Yeah, SSD manufacturers are doing this. But in another Intel SSD PDF I 
saw some graphs that convinced me in an instant that leaving free about 20% is 
a good idea. But heck, due to the current fill status of this SSD I do not even 
adhere to my own recommendation at the moment.

Then a occasional fstrim, maybe mount with noatime (cause who cares about it 
at all?)…

Ciao,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
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