procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
2 8 672 32680 137840 3049972 0 0 274 1723 0 3 8 4 80 9 0
1 6 672 44704 137708 3036556 0 0 21248 27210 1717 3238 18 4 58 20 0
2 5 672 63144 137792 3043872 0 0 7234 13382 1361 2946 12 5 66 17 0
0 4 672 52600 137924 3056888 0 0 8614 38788 1636 2631 10 4 62 24 0
1 5 672 46388 138036 3056240 0 0 9772 26620 1417 4211 16 4 61 18 0
3 1 672 48484 138060 3058532 0 0 12360 428 1830 3565 13 4 60 22 0
This is the o/p of vmstat in average performance time. Is it seems any problem as i am new to this statics?
Thanks,
Arvind S
"Many of lifes failure are people who did not realize how close they were to success when they gave up."
-Thomas Edison
On Tue, Sep 22, 2009 at 12:53 AM, Scott Whitney <swhitney@xxxxxxxxxxx> wrote:
The 2.5GB -> 50MB "problem" could mean a number of things. It could also
mean nothing at all. It's much more about the amount of swap (paging) space
that's being used at the time of the slowdown.
The fact that it runs fine for a few hour then degrades significantly would
point me in the direction of watching paging space consumption. You may have
added just one too many rows, making one query just big enough to make your
server start paging more than it ever used to do.
Check your vmstat and iostat information at the time of the slowdown, and
see if you can determine whether you're paging or waiting on storage. I
suspect you'll find that throwing hardware (memory, as a guess) at this
problem will solve it.
-----Original Message-----
From: S Arvind [mailto:arvindwill@xxxxxxxxx]
Sent: Monday, September 21, 2009 2:19 PM
To: Scott Whitney; pgsql-admin
Subject: Re: Postgres restart
Thanks Scott.
1. Well, is this a dedicated database server?
YES, it runs only Postgres with some Back-up script for that DBs alone
daily.
2. What O/S?
CentOS (Linux version 2.6.18-8.1.4.el5 (mockbuild@xxxxxxxxxxxxxxxxxxx) (gcc
version 4.1.1 20070105 (Red Hat 4.1.1-52)) )
3. What version of PG?
8.3.7
4. Have you check out memory usage?
When rebooted it has more then 2.5 GB free space but after few hours it
will reach 50MB. This is usual in our DB server, since this decrease never
affected our performance for past years. And also for 5 months we never
rebooted our system and also we had restart the postgres likely once in a
month, before this problem.
5. Also, when was the last time you vacuumed the database(s)?
As per advise from postgres team we are running full vaccum for every week
and frequently-used table(30) vacum daily. We have nearly 640 tables in each
DB.
6. Is auto-vac on?
Yes ( postgres: autovacuum launcher process running)
Is our problem is identifiable, from infrastructure side?
-Arvind S
"Many of lifes failure are people who did not realize how close they were to
success when they gave up."
-Thomas Edison
On Mon, Sep 21, 2009 at 11:33 PM, Scott Whitney <swhitney@xxxxxxxxxxx>
wrote:
There's an awful lot of information left out that would be very
useful to
help advise you.
Restarting the postgres services on a daily basis is certainly
nothing
that's going to corrupt your data or hurt your system, PROVIDED that
it is
done correctly (ie: not killing the backend postmaster when
something is
happening, not hard-booting the system while a RAID card is trying
to write
its cache, etc.)
However, I think you'd be postponing the problem. The better answer
might be
to define and resolve the issue.
"Its performance is good but gradually going down?" Well, is this a
dedicated database server? What O/S? What version of PG? Have you
check out
memory usage? 4GB seems a bit low for the amount of data you're
using. In a
similar environment, I've got 12GB, and from time to time I'm
paging.
If "nothing changed" (TRULY, that is), you're most likely finding
that
you're either CPU, memory, or I/O bound, and the most likely
culprits are
the last 2 unless you've suddenly started some massive queries that
didn't
happen a few weeks ago.
Also, when was the last time you vacuumed the database(s)? Is
auto-vac on? I
know, I know, I'm not _supposed_ to have to perform a full vacuum
and
analyze on my databases with auto-vac on, but if I don't, I run into
performance problems, so I do that once per week, myself.
-----Original Message-----
From: pgsql-admin-owner@xxxxxxxxxxxxxx
[mailto:pgsql-admin-owner@xxxxxxxxxxxxxx] On Behalf Of S Arvind
Sent: Monday, September 21, 2009 12:46 PM
To: pgsql-admin
Subject: Postgres restart
Recently due to some problem(not yet diagnosed) , our DB server
Postgres is
getting very slow after few hours. We didnt changed any settings for
6
months , so we dont know y its happening suddenly in this week. Our
data
folder is 118GB with 160 DBs. System is 2 Quad core with RAM 4GB. In
last
two days when it was restarted its performance is good but gradually
going
down. So few planned to restart the posgres process daily. Is it
advisable
to restart server daily ? since daily we can have 30 mins downtime.
Please
advise is it advisable or not?
-Arvind S
"Many of lifes failure are people who did not realize how close they
were to
success when they gave up."
-Thomas Edison
