eZDFS cache management

Thursday 07 January 2010 6:32:46 am

Hello :-)

I've never installed eZ Publish in eZDFS mode but I am wondering on the cache is managed :

Considering that the cache is stored locally on each front, when you edit an object for example : how the cache is cleaned for this object on each front ?

Thank you :-)

--
eZ certified developer: http://ez.no/certification/verify/346216

Thursday 07 January 2010 6:45:54 am

Based on your twitter response, it seems that the other thread doesn't explain that completely.

It is actually quite simple: the central repository for cache when using eZDFS is NFS (by default) + the ezdfsfile cluster table. The table is used to check the actual mtime, validity, etc. When a cache item is cleared, it is marked as expired in this table. When it gets regenerated, the item's mtime is modified in the table as well. Any other server of the cluster that further requests this cache file will compare its mtime in the DB to the local cache file's mtime.

So as soon as a cache item's mtime is changed in the DB, any local version older than this mtime will be replaced with the updated file.

Bertrand Dunogier
eZ Systems Engineering, Lyon
http://twitter.com/bdunogier
http://gplus.to/BertrandDunogier

Thursday 07 January 2010 7:17:37 am

NFS alone shouldn't make things THAT slow. It is bad, but not that much when it comes to speed.

In eZDFS, we chose to consider NFS as a simple files repository, and completely ignore it when it comes to metadata & concurrency handling (this is done using the database, as we have complete control over what the DB does).

Keep in mind that you will have a small loss of performances if you use eZDFS (usually around -10% page views), but cache updates will be completely transparent.

Bertrand Dunogier
eZ Systems Engineering, Lyon
http://twitter.com/bdunogier
http://gplus.to/BertrandDunogier