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

On Wed, June 3, 2009 13:44, Jennifer Trey wrote:
> 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
>

Jennifer,

I don't think it will tell you which files are being written to by which
process. That you'd need something else for and I don't know of any tools
that tell me that. I know DiskMon (also from SysInternals) will watch
your disk activity, but it doesn't show processes or filenames that I can
find.

Windows PerfMon will give you some detail. I get to it from a shortcut on
my Administrative Tools menu item: %SystemRoot%\system32\perfmon.msc /s
). (I don't know why there's a /s on the command line.)

You can add various performance counters to analyze the disk. But even
that is for the disk...not by process or application. I'm only able to
get a breakdown of processes doing disk i/o using Windows Task Manager
(unless someone else knows of a solution). And I don't know of a way to
capture and save that to make comparisons.

Tim

--
Timothy J. Bruce

visit my Website at: http://www.tbruce.com
Registered Linux User #325725