RE: IO load due to apache? Normal httpd behavior or script related?

[G VM <drums_gvm@xxxxxxxxxxx>]

> Likely a script problem, httpd wont cause harm
Did some further investigation and it seems APC (php opcode cache) generates this IO(or so it seems).
http://serverfault.com/questions/361032/high-disk-i-o-when-cache-is-used

> that is pretty ancient
RHEL. Not that ancient.

> ahhhhhhhhhhhhhhh so this is a VM
Yes :p any further point on this?

> If you are not sure what APC is then you cant need it and should disable it
Although I might not have a full understanding of what it does the customer is using it (passively). So disabling is not an option.
Sometimes disabling stuff from which you don't know what it does backfires ;)

One of these days I will be able to change the setting and verify that this fixed my problem.

Thanks for your response anyway:)

Grtz

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From: noel.butler@xxxxxxxxxx
To: users@xxxxxxxxxxxxxxxx
Date: Wed, 16 May 2012 10:12:47 +1000
Subject: Re: [users@httpd] IO load due to apache? Normal httpd behavior or script related?

On Mon, 2012-05-14 at 17:41 +0200, G VM wrote:

Hi all,

Recently I found out one server generating alot of load on our storage.

Likely a script problem, httpd wont cause harm

Linux 2.6.18-274.7.1.el5

that is pretty ancient

httpd     25431    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
httpd     25454    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
httpd     25622    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
httpd     25792    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
httpd     25794    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
httpd     25846    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
httpd     25849    apache  DEL       REG              253,3                   13 /tmp/apc.Fm8SAS
...

The only other is for sshd and another for vmware tools.

ahhhhhhhhhhhhhhh so this is a VM

If I try to do ls -lh /tmp/apc.Fm8SAS I get no such file or directory. Using the access time I would see if this file is accessed over and over again.
Am I missing something here? Is this apache doing a fstat() call for example?
Or is this file created and deleted over and over again at a very fast pace that I can't access it (this seems less likely to me).

Has anyone seen such behaviour in httpd? Or does someone knows a little more of the inner workings of httpd?

The name does me think that APC (sort of php module iirc) is having something to do with this:
apc.ini:apc.mmap_file_mask=/tmp/apc.XXXXXX

The config file seems to confirm this.

If you are not sure what APC is then you cant need it and should disable it