Your NFS server needs more RAM when…
… sometimes all your NFS processes are in the ‘D’ state (which essentially means the process is waiting for I/O).
(there is a picture here)
My usual strategy for busy NFS servers (or other file servers) is to have enough RAM to cache about 10% of the data it’s serving. This box is serving about 600G of data with 16G of RAM (of which 1/4 is gone to MySQL). I won’t likely get any money for RAM soon, so my strategy in solving this bottleneck is to move that huge 4.5G mysql process to another box (now that I have spare hardware). The RAM freed by this move will all go to file cache, thus reducing the load on the disks.
Mixing server roles on one box is never a good idea, but when I have to, I try to combine services that won’t fight for the same resources. DB servers are mostly CPU-bound, whereas file serving is I/O-bound. In this case, it has worked well for the first couple of years; however, as traffic (and data size) has increased, both the DB and the file server are fighting for precious RAM, and so they must be split.
Posted July 16th, 2008 by Denis Roy in category: Uncategorized
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nickb Says:
July 16th, 2008 at 10:59 pm
If you’re waiting for Io you might have to wait a while…
BTW, today’s CAPTCHA was “grepPG” — is blogger starting to use mod’d software terms, I wonder?