On Fri, 2007-12-14 at 01:54 -0500, Tom Lane wrote:
> "Merlin Moncure" <mmoncure@gmail.com> 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)