[horde] Horde performance with ActiveSync?

[Michael J Rubinsky]

Quoting Sebastian Arcus <s.arcus at open-t.co.uk>:

> On 10/04/18 18:05, Michael J Rubinsky wrote:
>>
>> Quoting Sebastian Arcus <s.arcus at open-t.co.uk>:
>>
>>> On 10/04/18 15:41, Arjen de Korte wrote:
>>>> Citeren Sebastian Arcus <s.arcus at open-t.co.uk>:
>>>>
>>>>> I have a Horde 5.2.17 + PHP 5.6.35 + Postgresql 9.2 + Lighttpd  
>>>>> 1.4.49 with 10 iPhones/iPads in ActiveSync/Exchange mode. The  
>>>>> users have fairly large Inboxes - some of them of 20 000+  
>>>>> emails. On IMAP that is not causing any issues, and hardly any  
>>>>> load on the server.
>>>>
>>>> Which IMAP server do you use? Is it local to the webserver?
>>>
>>> Thank you for replying. I use Dovecot which runs on the same  
>>> server as Horde.
>>
>>
>> Assuming the load you are seeing is still present after the  
>> devices' initial sync,
>
> Come to think of it, because after the initial setup all devices  
> have to re-download all headers, there is a good possibility that  
> 2-3 of them are still in the process of pulling down all their  
> headers (one of them has 80 000 just in the Inbox). I take it  
> downloading headers can be expected to generate a significant load?  
> On imap/Dovecot, the load was always negligible, but I suppose  
> ActiveSync+PHP/Horde is a completely different kind of beast.

Well, it would be very unusual for the EAS client to download ALL of  
the available email headers. Normally you would limit this to a  
specific time frame like the last 2 weeks or so. The Horde server  
takes care of expiring and refreshing the email on the client that  
falls within the requested time range. Older email would still be  
available via searching.

Even then, it normally only downloads the INBOX by default (unless the  
user explicitly sets other folders as "pushed").

If they really are, indeed, asking to sync the ENTIRE 80k+ messages in  
the INBOX, that will certainly take a bit of time, and I wouldn't  
doubt that the client might run into performance issues with that  
number of messages though I admittedly have no experience with that  
kind of message count on an iOS device.


> I am happy to let the initial sync finish on all devices, and then  
> see what kind of load is still present on the server.
>
> that kind of load makes me think there might be some sync
>> loop going on. Are the devices acting as expected? It might help to  
>> enable the activesync logging to see what is going on with the  
>> devices. Just actively listening for changes should be minimal  
>> load. Even with lots of mail being pushed and/or server intensive  
>> activities, like searching all email boxes only rarely bumps cpu  
>> usage over 10% for me. Like Arjen suggested though, make sure you  
>> have things like MODSEQ/QRSYNC enabled on your IMAP server. If you  
>> are using a default dovecot install, you probably already do, but  
>> it might be worth checking just in case.
>
> Dovecot is 2.2.33 which I compiled myself with default options.  
> There is also nothing unusual in the config file - definitely  
> nothing mentioning QRSYNC or MODSEQ. I can't seem to find any other  
> way to double-check these things are enabled - online searches seem  
> to suggest they are inbuilt capability since Dovecot 1.2 or so?

You could speak IMAP to your server and see what CAPABILITIES are  
reported, or better yet, enable the imap log on your horde server (see  
imp/config/backends[.local].php for details) which will show you this  
(among lots of other things).

>
>>
>> Also, some older iOS versions (thinking around iOS 7 or so if IIRC)  
>> had some major issues with ActiveSync, this is going back quite a  
>> while, but
>> thought I'd mention it just in case.
>
> Thank you. All devices are iOS 10+ - so this should probably not be the case.
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-- 
mike
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