[OPEN-ILS-DEV] big wads of RAM

[Reuben Pasquini]

Hi JF,

Just remember:

*. Your system will not be able to address more 
     than 4GB unless you install a 64bit version of Linux

*. Postgres will not be able to address more than 
      4GB unless you install a 64bit build of postgres.

Have you configured postgres to take
advantage of the memory you already have ?
The default postgres config is very conservative.
  
http://www.postgresql.org/docs/8.2/interactive/runtime-config-resource.html


Also, postgres may bog down over time
unless you regularly "vacuum"
and "reindex" the database.  
       http://www.postgresql.org/docs/8.2/interactive/maintenance.html
Newer version of postgres have an auto-vacuum 
capability.
    
http://www.postgresql.org/docs/8.2/interactive/runtime-config-autovacuum.html


Finally, you can get a sense of whether your memory is 
CPU or memory constrained by running 'vmstat' and 'top'
(sort by %MEM/%CPU in top).

top - 15:30:24 up 16 days,  3:16,  3 users,  load average: 0.00, 0.00,
0.00
Tasks: 165 total,   1 running, 162 sleeping,   1 stopped,   1 zombie
Cpu(s):  0.2%us,  0.1%sy,  0.0%ni, 99.6%id,  0.0%wa,  0.0%hi,  0.0%si, 
0.0%st
Mem:   2041944k total,  1993512k used,    48432k free,   300756k
buffers
Swap:  3229024k total,    35548k used,  3193476k free,   792724k
cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND   
       
    1 root      15   0  2952 1856  532 S    0  0.1   0:03.44 init      
        
    2 root      10  -5     0    0    0 S    0  0.0   0:00.00 kthreadd  
        
    3 root      RT  -5     0    0    0 S    0  0.0   0:00.22
migration/0        
    4 root      34  19     0    0    0 S    0  0.0   0:00.01
ksoftirqd/0        
    5 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/0
        
    ...

$ sudo vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system--
----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy
id wa
 1  0  35548  53092 300768 786732    0    0     1     8    7   13  0  0
100  0
 0  0  35548  53076 300768 786732    0    0     0   140   16  389  0  0
100  0
 0  0  35548  53076 300768 786732    0    0     0     0   21  352  0  0
100  0
 0  0  35548  53076 300768 786732    0    0     0     0    8  351  0  0
100  0
 0  0  35548  53076 300768 786732    0    0     0     0   14  359  0  0
100  0
....

Good luck!
Reuben


>>> "John Fink" <john.fink at gmail.com> 3/19/2008 11:37 AM >>>
Hey folks,

I'm in the midst of putting in a request for a bigger, beefier machine
on
which to run EG, seeing that the one I have now is encountering
postgres
problems with massive bib loads.  It seems like the most practical
amount of
RAM I can get with what I think my budget is will be 8gb.  Any
postgres
wizards care to comment whether or not this will be practical?

jf

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