Thanks Bret.
I'm curious about your classroom experience, if any, with the model selection
window in garp. We're seeing 30+ sec. waits for garp to read in all files in
the model directory before presenting the list of available times. This after
it has read in the oldest file in the directory as a template for the other
files (or so it seems when running garp in verbose mode). The performance does
not suggest caching is being done to advantage when 20 students are selecting
the model selection window at roughly the same time.
One may presume classroom garp usage to be history in about a year, but I'm not
sure the problem will not still be around in some form or the other.
-Neil
On Mar 29, 2011, at 10:04 AM, Bret Whissel wrote:
> If the server has sufficient RAM, then the first disk access will put the
> model data into kernel cache, and subsequent file access will read from RAM.
> It is more likely that the network connection will be the bottleneck. Of
> course, the first disk access may be faster with a SSD, and you have fewer
> concerns about media errors over the long haul. In contrast, if you have
> many different files being accessed (in which case the kernel disk cache
> doesn't provide much advantage), perhaps an SSD could improve throughput.
> (Be careful about the type of drive, however, as the NAND-type storage has a
> limited number of disk writes over the life of the drive.)
>
> (We run a classroom of 30 Linux workstations accessing NFS-mounted data from
> a NAS-type file server. We are generally pleased with performance.)
>
> Bret Whissel
> SysAdmin
> Earth, Ocean and Atmospheric Science Department
> Florida State University
>
> On Tue, 2011-03-29 at 09:43 -0500, Neil Smith wrote:
>> Was wondering if anyone has considered or made use of speed advantages of
>> solid state drives (SSD) for serving decoded ldm data to gempak, garp, and
>> too-be AWIPS2 processes running on network clients?
>>
>>
>> -- particularly in the classroom environment where visualization tools from
>> 20+ network clients are hitting the same $GEMDATA/models/<model> collection
>> at the same time.
>>
>>
>> When would SSDs be worthwhile? If the (NFS) clients are on a 100 Mbps
>> subnet and server is on separate 1000 Mbps subnet, is the network the
>> bottleneck, leaving modern drives or SSDs of negligible difference?
>>
>> -Neil
>> ---
>> Neil Smith neils@xxxxxxxx
>> Comp. Sys. Mngr., Atmospheric Sciences
>
>
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