[imp] Permformance issue

[Eric Rostetter]

Quoting Terry Poperszky <Terry.Poperszky@SosStaffing.com>:

> I am in the midst of converting a network that was entirely MS based to a
> mixed OS (Linux/MS) environment. MS Exchange is top on my hit list at the
> moment, but I have to provide suitable replacement services before I can
> replace it. Horde/Imp (Using IMAP) is the probable replacement for Outlook
> Web Access, but it simply isn't as quick as Web Outlook. I am looking to see
> whether that is inherent in the program, or is a function of my
> installation/infrastructure.

Are you hitting a seperate IMAP server, or the MS Exchange IMAP server, 
with Horde/IMP?  And what is your acceptable response time? (i.e. what
is the response time of the Web Outlook currently?)

Using a Dell 2400 2x600mhz, 512MB sdram, battery backed 128MB cache
raid controller with 6 disk Raid 5 logical volume for everything,
Postgresql/Horde/Apache/wu-ftpd with mbox format, RedHat Linux 6.x,
I can support 1000 users no problem.  And that is with the machine
doing other stuff too, and very heavy load.

Average time to open a mailbox of 1000 messages is about 1 second.  
Average time to retrieve a  message for display is about .4 - .8 seconds
depending on the message size.

Now, I've tested it also with other imap servers and other messages store
formats (wu-imapd without mbox format store) and it is even faster yet
with some other configs.  In my case, the message store (mbox) is a big
performance hit, but I like it anyway, and can live with the performance
hit.

So, your question is: is Horde/IMP slow, or something else?  I don't know.
But the most common non-Hore/IMP bottle necks would be database access, and 
imap server performance based on the underlying message store.  So this is
were I would check first if you don't think you are getting acceptible
performance for your hardware setup.

> My base network configuration revolves around three boxes (MySQL, SendMail,
> Apache/php)) all boxes are in running SuSE 8.0, have at least 800 Mhz
> processors, plenty of disk space and sufficient memory. They are connected
> via 100Mb FDX with their own ports on a central switch. I am not showing
> anything on the wire that would/should cause poor performance.

Sounds like your cpu, memory, disk, and network are sufficient.  So splitting
the boxes shouldn't result in any real performance hit.  Probably advantages,
since you don't have an SMP machine.  If I didn't have an SMP machine(s),
then I would probably split things up between machines asap.

On an SMP machine, I can service web requests, IMAP requests, and database
requests at the same time, and thus there isn't a real bottle neck.  On a
uni-processor machine, you can only do one at a time, and under any real 
load this will cause a bottle neck, and a bottle neck that can be eased 
by splitting between multiple machines.  So, if you are dealing with the
hardware you seem to say you have, then I would say you would probably 
get a big advantage, at least at high load times, by splitting your web
and IMAP services between two machines.

On the other hand, I run two installs of Horde/IMP on a two 2-cpu boxes,
everything on one box, without problem.  I also run it on a 4-cpu box
without problem.  I wouldn't want to do that on a slow, single cpu box
though -- even if average performance was okay, it would crash and burn
in certain situations...

> Terry Poperszky MCSE, CCNA
> Network Manager
> SOS Staffing Services 
> 801-257-5706
> Terry.Poperszky@SosStaffing.com

-- 
Eric Rostetter
The Department of Physics
The University of Texas at Austin

"TAD (Technology Attachment Disorder) is an unshakable, impractical devotion
to a brand, platform, product line, or programming language. It's relatively
harmless among the rank and file, but when management is afflicted the damage
can be measured in dollars. It's also contagious -- someone with sufficient
political clout can infect an entire organization."

--"Enterprise Strategies" columnist Tom Yager.