[horde] Horde ActiveSync - every few seconds disk write of the mysql database

[Michael J Rubinsky]

Quoting Samuel Wolf <samuel at sheepflock.de>:

> Hi,
>
> I wondering why my small home Horde server has every few seconds a  
> ssd access.
> Find out after some debugging with top/iostat/dstat it is a write  
> operation of the database.
>
> Nobody use the Horde Web interface at this time, only Smartphones  
> via ActiveSync are connected. As soon I stop the apache, the write  
> access stop as well.
>
> Is there something with ActiveSync which need every few seconds a  
> insert/update in the database?

There are a number of places where we need to save state to storage in  
ActiveSync. The most frequent cause of this would be during the start  
of various types of PING and SYNC requests where we save a timestamp  
and possibly other data (depending on the type of SYNC request). This  
is needed to prevent race conditions since clients may (and often do)  
initiate new SYNC/PING requests while a previous one is still running  
on the server. The timestamps are checked, and if a running request  
detects that there was a change in the various state/cache data it  
exits and yields to the new request.

If you have configured an artificially short heartbeat interval in  
your config, this may contribute to this, but now I'm just speculating.

Depending on how many devices you are supporting every few seconds may  
or may not be "normal". You can bump the Horde log up to DEBUG - where  
it will log all queries - and see exactly which INSERT/UPDATE write  
operation is running every few seconds and we can go from there.


-- 
mike
The Horde Project
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