[CalendarServer-users] Mac OS X Server

Don Kruse don at stahancyk.com
Thu Feb 5 17:52:18 PST 2009

I am finally following up on this issue as a few folks have asked me  
how our roll out of iCal server went.

Server Hardware:
Xserve 3.0GHz Quad-Core Intel Xeon 16GB RAM, 1.6TB RAID 5. (complete  

Mac OS X Server 10.5.6 (completely stock, no open-source mods) which  
runs iCal, iChat, and VPN. On our network we run Open Directory,  
Kerberos, and we manage our own internal DNS (all Mac OS X server  
based). Everything more or less works (although I can't even keep  
track of how many things I've kludged to "force" Apple server stuff to  
work the way it is supposed to. For example my DNS is a clean BIND  
install as I completely removed the Apple BIND setup yet it still  
plays nicely with the Server Admin GUI tool.

65 users with about 20 having pre-existing calendars from NUTD each  
with about 1400 events that were imported into iCal. All my users are  
using various Mac systems running 10.5 (with a few throwbacks on  
10.4). I expect that nearly all my users will give about 30-40 users  
read permissions to their calendars and 5-8 users read/write permission.

So what happened when I rolled it out this time?
As before it was very slow for all users on the first day which I  
expected. There are 52,079 events listed on the server, 56 user  
calendars so far and 16 groups. There have been some brief CPU spikes  
around 91% but the average CPU load works out to 26%. I am hoping that  
after a week or so it will start to average 18% - 20% during business  
hours. Before I loaded all the imported calendars and users started  
connecting the server load averaged just 2% with the same three main  
services running (iCal, iChat, VPN).

Once each user has their own calendar fully loaded as well as any  
delegated calendars the iCal client remains very responsive since  
events are first being cached locally. The background sync with 56  
users actively using the system has--so far--had little impact on our  
network. We have three satellite offices that connect over dedicated  
VPNs (sonicWALLs) so their connection speeds are not always very good  
but each local network is Gigabit ethernet and 802.11g wi-fi. After  
the initial day's surge the average bandwidth usage on the server is  
under 40 KB/s in/out with some spikes of course (at this point most of  
the data is outbound which makes sense).

It is sad that such a powerful server was required to host this system  
but I expect this is largely due to the fact that I was importing many  
pre-existing calendars from an earlier system. If the iCal system had  
been rolled out with initially empty calendars I might have been able  
to get by with a slightly lesser server (but in any case the dual G4  
Xserve would never had supported so many users).

- Don Kruse, IT Manager, Portland, OR

On Dec 8, 2008, at 9:31 AM, Don Kruse wrote:

> I ran iCal Server + iCal in a test environment on a older Xserve-- 
> Dual G4 1GHz 2GB RAM Mac OS X Server 10.5.5--in this test  
> environment with only a couple of test users and I noticed a  
> significant increase in CPU activity due to iCal but it seemed that  
> it wasn't something the server couldn't handle. A month later when I  
> rolled out the service to 60+ users the server was brought to its  
> knees. It ramped up to 100% CPU usage as more users logged in and by  
> about 11AM that business day it ceased to be functional. Anyone  
> trying to connect timed out before they received updates.
> I have not been able to track down any specifics as far as something  
> I can "fix" to prevent this problem as my iCal Server install is  
> Apple default and other than running the CPU load at 100% there was  
> not a single error reported/logged. I'm going to use brute force to  
> work around the issue but I would like to find a better approach.
> I am going to try to roll out this service again later today/ 
> tomorrow but hosted on a brand new Xserve 3.0GHz Quad-Core Intel  
> Xeon 16GB RAM (I'm lucky in that I work for a bunch of lawyers).
> I'll let you know what I find out and/or what happens.
> On Dec 6, 2008, at 11:11 AM, Louis ROMERO wrote:
>> Hello,
>> 	I have a 10.5.5 Mac OS X Server and the iCal Server is on. I have  
>> a problem, that happend twice, so I guess there is something.
>> 	On time, the CPU was at 100%, taken by the User, but I couldn't  
>> see what was wrong in Activity Monitor or top, because the step of  
>> measures was to large : I found that there were several small  
>> Python processes that were launched and stopped constantly !
>> I tried to know where they came from. I stopped services one after  
>> another, and found out it was iCal : 10% CPU after that.
>> Today, I had the same problem.
>> The only thing I did today with iCal Servr was augmenting a LDAP  
>> record in the OpenDirectory. I just chose the calendar to be synced  
>> with.
>> Where dos this come from ?
>> Thanks,
>> -- 
>> Louis Romero  Arcank
>> _______________________________________________
> Don Kruse
> Information Technology Manager
> tel 503-314-7361
> http://sam.stahancyk.com/helpdesk/

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