Fetch Cache issue.

[Taurus]

With the help of my hosting company I switched my Opcache Operator to Memcache yesterday. Everything seems to be fine. Although when I run the System test everything is OK except for the Fetch Cache option. Here I get this message:

Your Opcache Operator extension is functioning, however it is unable to store data. Please check your extension configuration.

Can you please help me in getting this right?

Thank you very much!

 

[Deceptor]

Hey Taurus,

With memcached this can mean a number of things so it's best to roll through them:

1) Have you updated your includes/config.php to enter your memcached server config? vBulletin have one listed there by default but it's commented out, those values are typically fine so uncommenting should do the trick - until vB Optimise confirms all tests with memcached I wouldn't integrate the vbulletin datastore cache with memcached in config.php just yet either.

2) Make sure memcached is running with allocated memory. If your host started the memcached daemon they will know how much memory is allocated, you'll need to check with them how much is available.

If both of those check out let me know and I'll try help you further, but that would mean something is wrong with the memcached installation/setup.

 

[Taurus]

According to my hosting company everything is correct in my config.php
I also checked and it seems to be correct.

2) Make sure memcached is running with allocated memory. If your host started the memcached daemon they will know how much memory is allocated, you'll need to check with them how much is available.

I am not sure where to check this.

This was the last response from my hosting company on applying memcache:

I'm going to increase the Memcache daemon's reserved memory pool, then let's see if this helps out. You should be able to check in the next 10-15 minutes to give the server time for filling up the cache.

 

[Deceptor]

You'd need to ask your host how much memory is allocated really, if they're being silly and giving you something like 8MB then it would fill up pretty fast. I'd recommend 64-128mb allocated, with TTL settings in vB Optimise then it should prevent memcached from becoming full.

 

[Taurus]

OK, this just in from my hoster:

It appears that the memory pool is set to 256MB. This is set in /etc/memcached.conf

 

[Deceptor]

That seems fine then - although from here the issue becomes server related and your host may know the cause of the issue, the problem being memcached is unable to "hold cache". Are they aware of the issue?

 

[Taurus]

Well, I don't know what to say. You say it is server related, and my hosting company just gave me this:

Memcahce(d) is definitely set up and running, so I would like to see how this is server related.

[root@host ~]# hostname ; ps aux | grep memca
host.creativx.net
root 12019 0.0 0.0 3076 724 pts/0 S+ 03:23 0:00 grep memca
nobody 30550 0.0 0.0 55076 1024 ? Sl Sep16 0:00 /usr/local/bin/memcached -u root -m 256 -p 11211 -u nobody -l 127.0.0.1

 

[Cosmic]

The message you are getting from vBO isn't vBO related - that is, it's not saying vBO isn't working or anything like that.

vBO is just checking if the cache system is working - that message means it's not working correctly. vBO hasn't changed or modified anything - it's just checking to see if memcache is functioning properly.

It's not physically possible for vBO to be "causing" that error, because it hasn't actually *done* anything =P

Deceptor may have an idea of a test your host can run to show that Memcache isn't functioning correctly.

 

[Taurus]

I understand that. But my hoster states that memcache is installed and working properly. So I dont get it anymore.

 

[Deceptor]

Looking at the command the user is issued twice:

/usr/local/bin/memcached -u root -m 256 -p 11211 -u nobody -l 127.0.0.1

note: -u root and -u nobody

Typically memcached runs under "nobody" for php to access it without issue and from the output that does seem to be the case. That said memcached isn't successful at "storing" cache which is why the test fails, the daemon is running without error yes - but something is wrong with it. Personally i'd try the following steps to resolve it:

1) Update the command so only -u nobody is issued, then restart the daemon
2) Ensure you have the pre-requesite for memcached install: libevent, if not install then restart the daemon
3) Make sure you have the latest php-memcache extension for PHP installed, if updated restart apache/memcache daemon
4) Download & install this to your site somewhere: http://livebookmark.net/memcachephp/memcachephp.zip, configure the username/password inside the PHP and memcache connection values, then try a few tests with vB Optimise and take a look at the hit/miss ratio on this debug page

Hopefully your host will help with these steps, just make sure they're clear on the actual issue: Memcache does not "retain/hold" data being sent to it through PHP, just because the service is running doesn't mean it's functioning. Unfortunately there's little else we can do as the system is just designed to outline issues with your extension, regardless let us know how it goes