[Dovecot] dovecot stats: useful data to gather

[Timo Sirainen]

On 1.6.2012, at 23.58, Patrick Ben Koetter wrote:

> Besides pulling together all the data we also think it would be useful to have
> an SNMP interface to access the stats.

I had thought about SNMP before also, but for the current kind of stats that are exported I couldn't think of any reasonable way to export them.

> Here are the stats we believe to be useful:
> 
> Login/Logout
> - total number login success/time
> - total number login failure/time
..

I'll look at these later in more detail, but some important questions / design decisions:

Currently stats process only remembers things after Dovecot was started. I don't think getting these kind of numbers would really work like that. Perhaps all of the statistics should be permanently dumped to disk every ~minute or so + at shutdown and loaded at startup, so the numbers would at least normally always just increase since the first time Dovecot was started?

> Mailbox state
> - Inflow rate (number incoming messages/time)
> - Deleted rate (number \Deleted flagged messages/time)

These operations/time type of things I had hoped to be able to externalize :) If stats process simply gives the raw stats, the reader could do this kind of summing up. Otherwise .. well, I guess it could maybe keep track of the current ops/<last 60 secs> and the reader would then have to read the value about once a minute or half or something. It wouldn't give exact results though.

> Performance
> - minimum time to write a message
> - maximum time to write a message
> - average time to write a message

Within last .. day? hour? minute? ..