Re: High I/O writes activity on disks causing images on browser to lag and not load

From: Bill Moran <wmoran(at)potentialtech(dot)com>
To: Jennifer Trey <jennifer(dot)trey(at)gmail(dot)com>
Cc: gryzman(at)gmail(dot)com, pgsql-general(at)postgresql(dot)org
Subject: Re: High I/O writes activity on disks causing images on browser to lag and not load
Date: 2009-06-03 19:59:58
Message-ID: 20090603155958.cc89bd22.wmoran@potentialtech.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-general

In response to Jennifer Trey <jennifer(dot)trey(at)gmail(dot)com>:

> Hmm, I just noticed the same write behavior on my Windows Xp laptop but the
> values was a little less.
> I even created an DB with one table and column and this still happened
> when querying it.

By "created", you mean you created a table and populated it with data?
Once you do that, do a "SELECT count(*)" on that table, then wait for
the I/O to calm down. That select statement will force all the hint
bits to be updated. See if subsequent selects still cause disk
activity.

> Are you sure that moving to Linux will solve this?

I never advocated that Linux would fix this, and I still don't. I
recommended a short list of methods to investigate the issue, most of
which you ignored. You _still_ don't know what's being written, and
I _highly_ recommend that you isolate that before doing something
radical like switching operating systems.

If you've got the DB configured in such a way that it's causing a lot of
write ops, it's going to do it in Linux or any other Posix systems, or
on CP/M for that matter.

Posix systems have a laundry list of tools to identify what programs are
doing. It's been a while since I've worked with Windows, but I seem to
remember MS having tools to audit disk activity. Turn them on and see
which files are actually being written to.

> Could you please check if
> you notice the same write behavior?

My BSD-based systems to no do this. Doing a select count(*) on a table
with 750,000 rows produces no write activity.

--
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/

In response to

Responses

Browse pgsql-general by date

  From Date Subject
Next Message Carlos Oliva 2009-06-03 20:06:17 Re: Upgrading Database: need to dump and restore?
Previous Message Scott Marlowe 2009-06-03 19:53:54 Re: High I/O writes activity on disks causing images on browser to lag and not load