Hardware and performance

This is exciting as I am back, NFS question

 
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This is exciting as I am back, NFS question
Particularly helpful Moodlers

Can Moodle access and read/write to Moodle data folder on NFS from 2 or more Apache Web-servers, without any issues?

My thoughts which are a little out of date, are that there is likely to be issues as NFS is not a clustered file system!. I am about to set up a 6 Apache node cluster with 2 x LB and Active/Passive MySQL and heartbeat

My memory is getting dim in my old age smile

Cheers

Albert

 
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Picture of Matteo Scaramuccia
Re: This is exciting as I am back, NFS question
Core developersParticularly helpful MoodlersPlugin developers

Hi Albert,
why not, especially using NFSv4 and some tuning at least on the mount point: https://moodle.org/mod/forum/discuss.php?d=367790#p1483926 .

HTH,
Matteo

 
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Re: This is exciting as I am back, NFS question
Particularly helpful Moodlers

Excellent I will have a look at the link.

Now what about the application as I have noticed on this system that I am taking over that the application is also shared on the NFS mount

I do not think that this is a good idea as the application should be as close to the web server as possible and I should just rsync the application across the 6 nodes periodically


Cheers

 
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Picture of Howard Miller
Re: This is exciting as I am back, NFS question
Core developersDocumentation writersParticularly helpful MoodlersPlugin developers

Make sure you set up a "proper" cache (e.g. Redis). NFS is rarely fast enough to provide decent performance for your cache (caching to 'moodledata' being the default)

 
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Re: This is exciting as I am back, NFS question
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We have four Memcached servers at the moment

But I am still wondering why we would have the application on an NFS share? I understand the moodledata folder but I would have thought that the application residing on the NFS share will slow it down considerably


Cheers

 
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Picture of Chris Fryer
Re: This is exciting as I am back, NFS question
 

But I am still wondering why we would have the application on an NFS share

My instinct would be to have wwwroot on local disk, but it doesn't much matter, I suppose, as long as you have opcache running. As soon as a PHP script is requested, it will be compiled and locked in memory on the web server. If you've set opcache.revalidate_freq to a suitably high number, Apache/PHP won't need to read from the NFS directory very often.

Of course there are other files, such as CSS and JavaScript, that are also served from wwwroot so you will want to ensure Apache is caching those locally.

https://httpd.apache.org/docs/2.4/mod/mod_file_cache.html

 
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Picture of Howard Miller
Re: This is exciting as I am back, NFS question
Core developersDocumentation writersParticularly helpful MoodlersPlugin developers

I obviously misread this. The application files. 

I'm not sure it hurts. NFS speed is always my big worry. For example, https://aimeos.org/tips/modern-php-applications-up-to-110x-slower-on-network-storage/

 
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Re: This is exciting as I am back, NFS question
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Exactly, I have never seen multi-node moodle application files stored on an NFS drive

I have always had the moodle application local to the web nodes and ran rsync to make sure they remain the same if I add or update something


Cheers

 
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Picture of Matteo Scaramuccia
Re: This is exciting as I am back, NFS question
Core developersParticularly helpful MoodlersPlugin developers

Hi Albert,
me too Yes: webapp locally stored, kept aligned via OS-dependent solution (rsync vs DFSR) or via versioning (git hooks).

HTH,
Matteo

 
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