[Beowulf] SSDs for HPC?

[Ellis H. Wilson III]

On 04/07/2014 09:34 PM, Prentice Bisbal wrote:
>> Was it wear out, or some other failure mode?
>>
>> And if wear out, was it because consumer SSDs have lame leveling or
>> something like that?
>>
> Here's how I remember it. You took the capacity of the disk, figured out
> how much data would have to be written to it wear it out, and then
> divided that by the bandwidth of the drive to figure out how long it
> would take to write that much data to the disk if data was constantly
> being written to it. I think the answer was on the order of 5-10 years,
> which is a bit more than the expected lifespan of a cluster, making it a
> non-issue.

This would be the ideal case, but requires perfect wear-leveling and 
write amplification factor of 1.  Unfortunately, those properties rarely 
hold.

However, again, in the case of using it as a Hadoop intermediate disk, 
write amp would be a non-issue because you'd be blowing away data after 
runs (make sure to use a scripted trim or something, unless the FS 
auto-trims, which you may not want), and wear-leveling would be less 
important because the data written/read would be large highly 
sequential.  Wear-leveling would be trivial under those conditions.

ellis