Re: [ldm-users] solid state drive(s) for ldm?

• To: Neil Smith <neils@xxxxxxxx>
• Subject: Re: [ldm-users] solid state drive(s) for ldm?
• From: "Larry D. Oolman" <ldoolman@xxxxxxxx>
• Date: Tue, 29 Mar 2011 08:54:25 -0600

I am not a Linux expert but I believe Linux caches disk IO in memory.
The first read of a data block would come from disk.  If there is
unused memory, successive reads of the same data block would be
out of memory until some other read ages it out.  If I am correct
on this, and your students are mostly trying to access the same
data, going to SSD drives may not get you much.  I've played
around with trying to put the LDM PQ file in memory and have
had only marginal improvement in performance.

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 <mailto:neils@xxxxxxxx>
Comp. Sys. Mngr., Atmospheric Sciences

--
Larry Oolman
Department of Atmospheric Science
University of Wyoming
Dept. 3038, 1000 E. University Ave.
Laramie, WY 82071
ldoolman@xxxxxxxx
http://www-das.uwyo.edu

• References:
  • [ldm-users] solid state drive(s) for ldm?
    • From: Neil Smith