Le 16/05/2014 02:35, Jim Henderson a écrit :
> On Thu, 15 May 2014 18:25:58 +0100, Orchid Win7 v1 wrote:
> 
>> On 15/05/2014 05:29 PM, Jim Henderson wrote:
>>> On Thu, 15 May 2014 08:21:51 +0100, Orchid Win7 v1 wrote:
>>>
>>>> All the PCs at work actually *have* these.
>>>
>>> Nonsense.  SSD drives are incomprehensibly expensive, and only the most
>>> well-off geeks have them because they're incredibly rare "in the wild".
>>> They must cost billions of dollars to purchase, most certainly. ;)
>>
>> Well *I* certainly couldn't afford one. But then, I'm not the one
>> paying, so... ;-)
> 
> Only the top 1% could possibly afford them.  Even then, it's little more 
> than a curiosity, the only ones who really benefit from them surely are 
> the top 0.1%.
> 
>> As I say, there's not much real-world observable performance difference,
>> to be honest.
> 
> You obviously aren't using the ones that I'm talking about.  ;)

SSD or HDD or SSHD ? (solid state drive, hard drive (traditional), solid
state hybrid hard drive).

There is also in SSD two categories: SLC and MLC (single bit in a cell,
vs multiple bits in a cell) (as well as some other exotic ones). (in
fact, M of MLC now means 2, and the emerging TLC is with T for 3): the
more bits per cells, the less number of warranted write per cell. (but
when you change a sector's content, the SSD does not write it at the
same cells, the firmware uses some fresh cells for the new value, so the
number of actual erasure is spreads on all the available cells).
TLC has a 1000 write warrant, when MLC has between 3000 and 5000 and SLC
above 20000.
(and the market trend is to go to TLC !)

SSD vs HDD: the cost for capacity is about ten to twentyfold so far.

The top-available capacity is also lower for SSD ( current value is
about a quarter of terabyte, when three terabytes on HDD, both going for
the psychological price of 100€ )

The read performance is also about x10 in the opposite direction (SSD
has far less seek time, and faster data pump). Yet real write is subject
to caution: HDD has seek time but write 4k easily, whereas SSD has a
bigger chunk to copy even if you modify only a few bytes. If you
consider the whole chunk, the write speed is similar. but if you write
many small files, it sucks.

And if we go on the road of luxury, there is the EFD (enterprise flash
drive), a kind of SSD made for high I/O performance and more.

The SSHD (ssd within a traditional hard drive) might have a card to
play: the system can be copied/cached on the ssd, but all the
event-logger and dynamic files stay on the rotating media. And it should
be transparent to the OS, as the firmware is going to select sectors
which are read often and nearly never written... if they do it right.

-- 
Just because nobody complains does not mean all parachutes are perfect.

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