Re: Need to find out which process is hitting hda

On Fri, 2007-12-14 at 01:54 -0500, Tom Lane wrote:
> "Merlin Moncure"  writes:
> > there are a few things that I can think of that can can cause postgres
> > to cause i/o on a drive other than the data drive:
> > * logging (eliminate this by moving logs temporarily)
I'll have to try this

> > * swapping (swap is high and changing, other ways)
> > * dumps, copy statement (check cron)
Not doing any of these

> > * procedures, especially the external ones (perl, etc) that write to disk
Nope. the only perl running is just pulling data from the master DB into
this little box


> 
> > my seat-of-the-pants guess is that you are looking at swap.
> 
> vmstat would confirm or disprove that particular guess, since it tracks
> swap I/O separately.

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  6 300132   5684   4324 315888  420   32  1024   644 1309  485 35 11  0 54  0
 0  6 299820   6768   4328 313004  588   76  3048   576 1263  588 36 12  0 52  0
 0  6 299428   5424   4340 313700  480   36  2376   104 1291  438 24  9  0 67  0
 2  6 298836   5108   4268 313788  800    0  2312   216 1428  625 30 10  0 60  0
 2  6 298316   5692   4192 313044  876    0  1652  1608 1488  656 33 11  0 56  0
 2  6 298004   6256   4140 312184  560    4  1740  1572 1445  601 42 11  0 47  0

I kept looking at the io columns and didn't even think of the swap
partition. It's true that it's moving quite erratically but I won't say
that it's really thrashing. 

             total       used       free     shared    buffers     cached
Mem:           503        498          4          0          3        287
-/+ buffers/cache:        207        295
Swap:         2527        328       2199

(YEP, I know I'm RAM starved on this machine)