Hello friends
I have a problem with buffers and cache.
Box 1: 512MB RAM, CentOS 4.1, kernel 2.6.9-11.EL
Box 2: 1GB RAM, CentOS 4.2, kernel 2.6.9-22.0.1.EL
In all other respects identical. I just moved my site from 1 to 2, kept everything exactly the same. Load on 1 averaged about 0.04, but on 2 it averages 0.50. Crazy considering 2 is the better machine!
I believe it's due to buffers / cache, which I think are causing HDD reads to queue up.
Note these outputs from 'free' - box 1:
Code:
total used free shared buffers cached
Mem: 515108 394228 120880 0 49700 279080
-/+ buffers/cache: 65448 449660
Swap: 1052248 0 1052248
And box 2:
Code:
total used free shared buffers cached
Mem: 1031740 178676 853064 0 144 23044
-/+ buffers/cache: 155488 876252
Swap: 1052248 14816 1037432
Tell me that isn't WEIRD for a well loaded server. Tiny buffers and cache!
I've looked everywhere but can't find a tweak for forcing larger buffers + cache. What can I do short of attempting a kernel downgrade? Any ideas will be greatly appreciated.