[Pw_forum] SATA vs SAS

[Axel Kohlmeyer]

On Thu, Aug 7, 2014 at 6:56 AM, siddheshwar chopra <sidhusai at gmail.com> wrote:
> Dear Sir,
> Oh I am sorry... I think I didn't mention correctly.. I said "write times"..
> It is actually "number of write times". Ofcourse these are very fast..But
> their life is shorter than the normal HDDs...
> Yes budget is what is the final verdict.. :-)

not only that. but also, how much time you save, i.e. how much value
you attribute to your own time.
if an SSD will wear out and become unusable, you can easily replace it
at the fraction of the cost of the entire machine, and then - provided
an SSD scratch does significantly improve your calculation run times -
you have a faster machine all the time.

please also note that SSD performance varies a lot and also the amount
of guaranteed writes.

axel.


>
> Regards,
>
>
> On Thu, Aug 7, 2014 at 4:18 PM, Carlo Nervi <carlo.nervi at unito.it> wrote:
>>
>> I'm not an expert, and maybe my infos are old, but I think you are wrong.
>> Certain SSD have degraded performances, however the best SSD have much
>> faster access I/O time than than the best HDD. at least for medium
>> workstation. Cost for Gb is of course much higher for SSD, but in this case
>> I would go only for a working directory to be placed on a SSD partition (128
>> Gb could be enough). I do not know how is the situation for high-end
>> enterprise solutions or supercomputers, but in this case i suspect that the
>> special HDDs are not connected via simple SATA or SAS, and in these cases
>> very probably they are much faster (again at much hgher prices) due several
>> optimized performances (independent memory cache, for example).
>>
>> In other words, it depend how much is your budget...
>> Cheers,
>>  Carlo
>>
>>
>>
>> 2014-08-07 11:42 GMT+02:00 siddheshwar chopra <sidhusai at gmail.com>:
>>>
>>> Dear Sir,
>>> I just want to participate in this good discussion. I read somewhere that
>>> Solid State Hard Disk has LESSER write times than a normal HDD. Yes
>>> undoubtedly it is the fastest we have in the market with low power
>>> consumption and zero mechanical failure risk, but at the cost of shorter
>>> lives and more money.
>>> Any comments welcome..
>>>
>>> Regards,
>>>
>>>
>>> On Thu, Aug 7, 2014 at 2:16 PM, Carlo Nervi <carlo.nervi at unito.it> wrote:
>>>>
>>>> My two cents: even though there are differences between SAS and SATA,
>>>> they are not so huge.
>>>> From this point of view I guess that a fast Solid State Hard Disk would
>>>> make the difference on the I/O.
>>>>
>>>>
>>>>
>>>> 2014-08-07 10:06 GMT+02:00 Paolo Giannozzi <paolo.giannozzi at uniud.it>:
>>>>
>>>>> On Wed, 2014-08-06 at 18:15 -0400, Eduardo Menendez wrote:
>>>>>
>>>>> > Is it critical to use SAS disks (compared to SATA) for good
>>>>> > performance of Quantum ESPRESSO?
>>>>>
>>>>> I guess it depends upon the amount of I/O you plan to do
>>>>>
>>>>> Paolo
>>>>>
>>>>> --
>>>>> Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
>>>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>>>>> Phone +39-0432-558216, fax +39-0432-558222
>>>>>
>>>>> _______________________________________________
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>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> ------------------------------------------------------------
>>>> Prof. Carlo Nervi carlo.nervi at unito.it  Tel:+39 0116707507/8
>>>> Fax: +39 0116707855      -      Dipartimento di Chimica, via
>>>> P. Giuria 7, 10125 Torino, Italy.    http://lem.ch.unito.it/
>>>>
>>>>
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>>>
>>>
>>>
>>> --
>>> Dr. Siddheshwar chopra,
>>> M.Sc., Ph.D (Physics)
>>> Assistant Professor (Physics),
>>> Amity University, Noida, India.
>>>
>>>
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>>
>>
>>
>> --
>>
>> ------------------------------------------------------------
>> Prof. Carlo Nervi carlo.nervi at unito.it  Tel:+39 0116707507/8
>> Fax: +39 0116707855      -      Dipartimento di Chimica, via
>> P. Giuria 7, 10125 Torino, Italy.    http://lem.ch.unito.it/
>>
>>
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>
>
>
>
> --
> Dr. Siddheshwar chopra,
> M.Sc., Ph.D (Physics)
> Assistant Professor (Physics),
> Amity University, Noida, India.
>
>
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-- 
Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.