Apache not showing/serving images.

I had originally sent this to 2 other lists but received minimal
suggestions so I thought I would try here as well.
Here goes:
__________________________________________________ __________
Original
I am running into an issue where a client's server is intermittently
throwing invalid 404 errors. I can't for the life of me figure it out.
There is a web app that pulls up client previews of their ads.
Intermittently the page loads with the image missing. When I view
source on the page, the correct path is there. I copy and paste the
url (which I have fully qualified) into a new tab and it also
intermittently show up. Hitting refresh several times or selecting the
url bar and hitting enter will make the image pop up. It is not
isolated to any one browser. It happens to all of them. For example
here is a url:
http://adserver.saguarogold.net/20070220162109.jpg
For example to prove the intermittency, right now I can refresh that
url over and over and it loads fine. If I load it from the web app and
it fails, then copy the url to a new tab and try it also fails. BUT
again, hitting enter in the url bar or refresh several times it works.
Originally I had the images served via an alias to another folder but
decided to go the route of its own virtual host but yet this still
happens even when directly served.

Has anyone else seen this intermittency? This has been costing me a
lot of grief for some time now. I am at the point of wiping the drive
clean and reinstalling Mac OS X Server to 10.4 and see if this solves
the problem.

Anything to check for or turn on in the config?

__________________________________________________ __________
Replies:
To summarize the scenario thus far I have heard the following:

1. Check the persistent connections.
2. Server caching - 2 places.
3. image expiry.


As far as #1, the server is set with the default settings that had
previously been fine.
Max simultaneous connections : 500
Max persistent connections : 500
Connection timeout 300 seconds
Minimum spare servers : 1
Maximum spare servers : 5

Onto #2... There is only 1 place that I can find where you can control
Apple's caching server. That is from the domain level. I went thru and
made sure that was unchecked on every domain so it must be off. Where
is the server level that was mentioned?

As for #3, what has image expiry have to do with it? If a file exists
and I can see it in the directory but when calling the URL and get a
file not found error 1 second and then no error the next, how is it
expiry? Is it possible that Apache's virtual host system is crapping
out and defaulting to the default site where the file definitely does
not exist?

On Feb 22, 7:05 am, Davide Bianchi <davideyeahs...@onlyforfun.net>
wrote:
> On 2007-02-22, Steffan <stef...@hldns.com> wrote:
>
> > I am running into an issue where a client's server is intermittently
> > throwing invalid 404 errors. I can't for the life of me figure it out.
>
> If something is 'intermittent', by definition is impossible to solve. You
> should try to nail down when it happens and what are the circustamces,
> like 'hi load of the server', 'i/o errors on disk' and so on. Like this,
> you could blame it to the Greemlins...
>
> > Anything to check for or turn on in the config?
>
> Without knowing anything, I'll say, just grab the log files when it
> happens and have a look at them, try to see a pattern in the events.
>
> Davide
>
> --
> Trying to get Windows to run on the hardware that Linux typically runs on
> is like pushing an elephant through a keyhole.
> -- Forbes Magazine

I can say that the server load is MINIMAL because it is only being hit
by about 150 at different times. Well beneath the capacity of Apache.
There are no errors on the HD per the disk util. I'll check the logs
today and post back here with the errors from the logs.

Thanks for the suggestions
-Steffan

On 22 Feb, 14:13, "Steffan" <stef...@hldns.com> wrote:
> On Feb 22, 7:05 am, Davide Bianchi <davideyeahs...@onlyforfun.net>
> wrote:
>
>
>
> > On 2007-02-22, Steffan <stef...@hldns.com> wrote:
>
> > > I am running into an issue where a client's server is intermittently
> > > throwing invalid 404 errors. I can't for the life of me figure it out.
>
> > If something is 'intermittent', by definition is impossible to solve. You
> > should try to nail down when it happens and what are the circustamces,
> > like 'hi load of the server', 'i/o errors on disk' and so on. Like this,
> > you could blame it to the Greemlins...
>
> > > Anything to check for or turn on in the config?
>
> > Without knowing anything, I'll say, just grab the log files when it
> > happens and have a look at them, try to see a pattern in the events.
>
> > Davide
>
> > --
> > Trying to get Windows to run on the hardware that Linux typically runs on
> > is like pushing an elephant through a keyhole.
> > -- Forbes Magazine
>
> I can say that the server load is MINIMAL because it is only being hit
> by about 150 at different times. Well beneath the capacity of Apache.
> There are no errors on the HD per the disk util. I'll check the logs
> today and post back here with the errors from the logs.
>
> Thanks for the suggestions
> -Steffan

It worked fine for me.

Do you have a network protocol analyser, like wireshark, if so, use it
to see what the packets look like, every error will show up there, and
is IMHO the best possible way to actually nail down whats going wrong,
you may not be able to spot a pattern otherwise. It even colourises
them and you can watch them in real time!
For instance we had a guy recently who in the end just reinstalled the
OS! (It wasnt a MAC dont worry) I didnt seem to be ble to convince him
to go the packet inspection route - so none of us were any the wiser
when he triumphantly said "it works now".

Every time I install a Linux or *nix box here I have to lower the MTU
to 1490 or else I get intermittent problems with images. (Actually I
get intermittent problems with all sorts but they show up most with
images, especially in firefox which is sensitive to corruptions within
images, which is as it should be!!!)

If the packet log shows fragmented HTTP TCP packets, alot of
retranmissions etc... you are nearer to solving the problem.

If you see RST packets again you are nearer.

I was that guy! I tried wireshark and it showed no problems., so it was
quicker to reinstall,
It was fairly obvious that it was not a network problem from the begining

"shimmyshack" <matt.farey@gmail.com> wrote in message
news:1172168525.740525.28300@v33g2000cwv.googlegro ups.com...
> On 22 Feb, 14:13, "Steffan" <stef...@hldns.com> wrote:
>> On Feb 22, 7:05 am, Davide Bianchi <davideyeahs...@onlyforfun.net>
>> wrote:
>>
>>
>>
>> > On 2007-02-22, Steffan <stef...@hldns.com> wrote:
>>
>> > > I am running into an issue where a client's server is intermittently
>> > > throwing invalid 404 errors. I can't for the life of me figure it
>> > > out.
>>
>> > If something is 'intermittent', by definition is impossible to solve.
>> > You
>> > should try to nail down when it happens and what are the circustamces,
>> > like 'hi load of the server', 'i/o errors on disk' and so on. Like
>> > this,
>> > you could blame it to the Greemlins...
>>
>> > > Anything to check for or turn on in the config?
>>
>> > Without knowing anything, I'll say, just grab the log files when it
>> > happens and have a look at them, try to see a pattern in the events.
>>
>> > Davide
>>
>> > --
>> > Trying to get Windows to run on the hardware that Linux typically runs
>> > on
>> > is like pushing an elephant through a keyhole.
>> > -- Forbes Magazine
>>
>> I can say that the server load is MINIMAL because it is only being hit
>> by about 150 at different times. Well beneath the capacity of Apache.
>> There are no errors on the HD per the disk util. I'll check the logs
>> today and post back here with the errors from the logs.
>>
>> Thanks for the suggestions
>> -Steffan
>
> It worked fine for me.
>
> Do you have a network protocol analyser, like wireshark, if so, use it
> to see what the packets look like, every error will show up there, and
> is IMHO the best possible way to actually nail down whats going wrong,
> you may not be able to spot a pattern otherwise. It even colourises
> them and you can watch them in real time!
> For instance we had a guy recently who in the end just reinstalled the
> OS! (It wasnt a MAC dont worry) I didnt seem to be ble to convince him
> to go the packet inspection route - so none of us were any the wiser
> when he triumphantly said "it works now".
>
> Every time I install a Linux or *nix box here I have to lower the MTU
> to 1490 or else I get intermittent problems with images. (Actually I
> get intermittent problems with all sorts but they show up most with
> images, especially in firefox which is sensitive to corruptions within
> images, which is as it should be!!!)
>
> If the packet log shows fragmented HTTP TCP packets, alot of
> retranmissions etc... you are nearer to solving the problem.
>
> If you see RST packets again you are nearer.
>

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