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

On Wed, Jun 3, 2009 at 10:59 PM, Bill Moran <wmoran(at)potentialtech(dot)com>wrote:

> 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.
>

No, I created a new DB, created a table, and did not even populate any
data.

Running select count(*) from test

just now, still caused the 10-20 I/O-writes.

>
> > 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.

I didn't ignore all of them.
When it comes to the logging I am still not sure. What file should I be
looking at ? The standard log file currently has 5 lines in it, and its only
errors.
When it comes to things set as wrong, it might be true. However, on the
laptop I've only installed and ran Tuning Wizard and haven't touched it
afterwards.

No, I still don't know whats being written. I have tried to isolate it, and
checked several folders, but can't find the path.

The statement i made earlier about how there was no reads was false. There
is reads and they are done mostly by another thread. I was checking the same
process at that time. However, the combined sum of I/O shows that there are
more writes than reads with postgresql. Currently on the server by 2.25

>
>
> 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.
>

I will try to find such a tool.

>
> > 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.
>

Thats good to know.

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

Grzegorz, i have considered the hosting solutions. Problem is money. I am
still a student. I might take you up on the other offer though :)

Scott, how much would such a controller cost me?

Tim, yes, I am using the tool "ProcessExplorer" from the windows site. It
shows all the activity but can't see to where those writes are being done
with that tool. Any ideas?

Thanks all, appreciate all your help and effort.

Sincerely / Jennifer