[horde] cache question

[Niels Dettenbach]

Am Freitag 28 Januar 2011, 00:33:28 schrieb Paras pradhan:
> I think enabling this cache is highly recommended. Should I use file
> or other driver? which one is recommened?

hmmm,
i did not tested horde with all of the available caching backends, but i 
assume there is no general answer which of the backends gives most "effect" as 
your expectations may differ from that of others and it depends from the 
underlying system environment too.

We mainly used eAccelerator driver in the past and apache's cache mechs (i.e. 
mem cache). For different reasons we run the eAccelerator disk storage on a 
tempfs at several machines with i.e. slow storage backend (i know that 
eAccelerator offers RAM caching byself) - especially with slower SAN backends. 
As caching was removed from eAccelerator > 0.9.5 (as i.e. stated within the 
Horde admin panel) we switched over to APC (which should get into the PHP 
upstream with PHP 6).

Several independent benchmarks get results i.e. that eAccelerator and Zends 
optimizer is faster then APC - but i did not see any significant difference in 
practice.

The efficiency and performance of a file based cache storage highly depends 
from your storage topology / I/O-system - i.e. many SATA and/or multi-user SAN 
topologies could be act as a significant "bottleneck".

If you are able to spend a lot of RAM for caching and especially if your 
storage system is "slow" or near his limits you should prefer RAM. If RAM is 
"expensive" and your storage system is able to perform a fast handling of 
concurrent read requests you may decide for file based storage.

If your SQL backend runs i.e. on a significantly faster system / machine (or 
you did not have any other choice) system then your horde SQL caching might be 
the best choice.

But not at least - even your operating system and OS tunings could affect the 
performance within the different caching solutions (i.e. as they often 
interfer with OS own optimization techs or OS limits).

Our experiences with memcached in the past did not match our expectations 
(plus there was several security flaws in the past within memcached) - so we 
did not use it anymore. May be this is a wrong decision. One interesting part 
is that memcached could run even on another / exteral machine.

So we are still interested in further experiences here.


cheers,

Niels.


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  Niels Dettenbach
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