many ssds carry 3-year warranties and report useable life via smart. if you are 
concerned about wearing them then buy a spare or two and rma them as they 
approach burn out. 

that is what i do :)

Sent from Jasons' hand held

On Aug 8, 2012, at 9:24 AM, Reginald Beardsley <[email protected]> wrote:

> Order of magnitude I already knew.  I was hoping for measured data.  I'm 
> running Solaris 10 on this particular system.  The OI box is a nettop for 
> Internet access.
> 
> I'm concerned w/ occasionally running jobs which exceed physical memory.  At 
> most I can only go up to 24 GB by replacing all the 2 GB DIMMS w/ 4 GB DIMMS. 
> 
> However, I'd not considered the problem of pathological paging patterns.  On 
> a long job one might well wear out an SSD in a single run which would not be 
> helpful.  I don't think I want to try to figure out what the paging patterns 
> of a large solver like glpk are.  Particularly because it almost certainly 
> problem and option dependent.
> 
> A dedicated pair of small, fast disks for swap is probably the best option. 
> To the best of my knowledge Solaris will still interleave paging among 
> multiple swap partitions on separate drives. This was something I routinely 
> did on my systems for many years.
> 
> IIRC two matched drives were almost twice as fast as one. It was essential 
> that the drives have identical performance, otherwise it actually slowed the 
> system down.  I vaguely recall that more than two didn't improve performance, 
> but it was a long time ago.  I may not have had 4 identical drives.
> 
> Have Fun!
> Reg
> 
> --- On Wed, 8/8/12, Jan Owoc <[email protected]> wrote:
> 
>> From: Jan Owoc <[email protected]>
>> Subject: Re: [OpenIndiana-discuss] SSD swap space performance
>> To: "Discussion list for OpenIndiana" <[email protected]>
>> Date: Wednesday, August 8, 2012, 10:39 AM
>> On Wed, Aug 8, 2012 at 8:49 AM, Udo
>> Grabowski (IMK)
>> <[email protected]>
>> wrote:
>>> On 08/08/2012 16:47, Reginald Beardsley wrote:
>>>> 
>>>> Has anyone done any testing on the performance of
>> an SSD for swap vs disk?
>>>> I'm currently fully populated at 12 GB in my Z400.
>>>> 
>>> That should work, but if you really need a fast SSD
>> for
>>> regularily swapping, you may should start thinking
>> about
>>> more memory...
>> 
>> I haven't done testing on OpenIndiana, but in my experience
>> swap on an
>> SSD is an order of magnitude faster than swap on HDD. Note
>> that, as
>> Udo pointed out, this is still an order of magnitude (or
>> two) slower
>> than additional RAM.
>> 
>> If your workload is such that you have large chunks of
>> memory that can
>> be swapped out for extended periods of time, then an SSD
>> will do this
>> several times faster. However, if you have a program that is
>> actively
>> using more than the 12GB of RAM you have, you will kill your
>> SSD (SSDs
>> have a limited number of write cycles - each time you'd run
>> the
>> program, loads of data would hit the SSD) and won't get
>> anywhere near
>> the performance of actually having adequate memory.
>> 
>> Jan
>> 
>> _______________________________________________
>> OpenIndiana-discuss mailing list
>> [email protected]
>> http://openindiana.org/mailman/listinfo/openindiana-discuss
>> 
> 
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