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Re: Login nightmare


On 25 Jan 2008, at 15:26, Nick Kutzko wrote:

That's not encouraging =(

I suppose it's doable, but the problem is I don't like to use RAID 0 or 0+1,
I'd rather do 5 or even 6 if I had to. That will cost more money than the
powers that be will allow, since we're already overbudget due to a huge
number of failing eMacs.

Also, why would it be so much worse with 10.5 than 10.4? We had slow logins
before, but nothing THIS bad.

Yes, sorry, I hadn't seen the rest of the posts on the subject... while I still think that your disk is probably overworked it does sound like (as someone else suggested) some kind of transient network problems. There nothing in the trace you sent to suggest dodgy DNS, and the AFP connection gets going within the first couple of seconds.

IF you could get a trace of a complete slow login (from clicking "login" to Finder being up) along with timings for how long the login actually took, we might be able to discern what (if any) the problem with the network is...

-geoff 


On 1/25/08 9:16 AM, "Geoff Lee" <email@hidden> wrote:


On 25 Jan 2008, at 15:07, Nick Kutzko wrote:

2GHz G5 Xserve, 2GB RAM, 450GB.  Home directories are on a separate
drive
from the OS, if that matters.


If you're trying to support 30 simultaneous logins from one disk
spindle, I'd say that's your problem... think of the amount of work
that one disk is trying to do reading 30 Preference folders
simultaneously! I'd think seriously about setting up at least a
striped RAID or possibly using local accounts on the machines and
redirecting the documents folders (this is what I do).

Cheers,

-geoff 



On 1/25/08 9:04 AM, "Geoff Lee" <email@hidden> wrote:


On 25 Jan 2008, at 15:02, Nick Kutzko wrote:

No, the machhine didn't take a half hour to log in, the trace ran
after.  I
wasn't sure how long I was supposed to let it run.

That webserver might be the server for the website the kids were
using that
day. They were doing some kind of activity that had a lot of flash
animation and whatnot.

The OD server's nighest CPU that day was around 80-90%, but the
network
throughput is only 3MB/sec.  Does that seem right?  So much power
and so
little traffic?


If it's thrashing the disks around a lot, that's not really
surprising.  What are the specs of your server (Disk, CPU, RAM)?

-geoff 



On 1/25/08 6:24 AM, "Geoff Lee" <email@hidden> wrote:


Hi,

On 23 Jan 2008, at 15:39, Nick Kutzko wrote:

Here's the output file. I'd appreciate anything you can tell me. 

It raises a few questions...

Did the machine really take half an hour to log in, or was the
trace
running after it finished?

What is the webserver at 206.166.93.137 doing (actually I don't
think
this is important, it just seems to generate a lot of traffic at
the
start if the trace).

What is the load on your AFP server during these logins? How much
RAM
does it have?

Really all I can see from the trace is that there is a _lot_ of AFP
activity and that it takes a long time, This may indicate that your
AFP server simply can't handle that number of people logging in
simultaneously: it causes huge amounts of disk activity...

If you could do a similar trace of a quick login by the same
account
for comparison, it might shed some more light on the situation...

HTH

-geoff 



On 1/23/08 9:23 AM, "Geoff Lee" <email@hidden> wrote:


On 23 Jan 2008, at 15:18, Nick Kutzko wrote:

I did the dump, but I can't find the file.  Where does it save
to?


You should end up with a file called slowlogin.tcpdump in your
working
directory.

-geoff 



On 1/23/08 6:11 AM, "Geoff Lee" <email@hidden> wrote:

Hi Nick,

On 22 Jan 2008, at 20:37, Nick Kutzko wrote:

Our users are taking anywhere from 2-5 minutes to login
through
OD.
I have
tested users, groups, computers, the servers and I'm totally
lost.
Sometimes, they don't even get logged in for half of a class
period. My
account logs in quickly, less than 30 seconds, and when I
tested
users
individually they were equally fast. However, come class time
when
they all
try to log in (25 kids, roughly) it lags or locks up. Any
suggestions? I
tried using a folder redirect through WGM, but it doesn't seem
to
help. 

A packet trace can be invaluable in these situations. SSH
into a
machine and run

tcpdump -vvv -i en0 -s0 -w slowlogin.tcpdump

Now log into the machine as a student and wait... Hit ctrl- C on
your
monitoring machine once the process has finished.

Then pop open the tcpdump file in wireshark (formerly ethereal,
available from darwinports) and have a look-see.

If this sounds daunting, feel free to mail me the output file
from
tcpdump and I'll have a look...

HTH

-geoff

______________________________________
Geoff Lee <email@hidden>
Computing Support
School of Arts, Culture and Environment
University of Edinburgh
20 Chambers St,
Edinburgh, Scotland,
EH1 1JZ
Tel: +44 (0)131 650 2341
______________________________________









______________________________________
Geoff Lee <email@hidden>
Computing Support
School of Arts, Culture and Environment
University of Edinburgh
20 Chambers St,
Edinburgh, Scotland,
EH1 1JZ
Tel: +44 (0)131 650 2341
______________________________________







<slowlogin.tcpdump.zip> 

______________________________________
Geoff Lee <email@hidden>
Computing Support
School of Arts, Culture and Environment
University of Edinburgh
20 Chambers St,
Edinburgh, Scotland,
EH1 1JZ
Tel: +44 (0)131 650 2341
______________________________________









______________________________________
Geoff Lee <email@hidden>
Computing Support
School of Arts, Culture and Environment
University of Edinburgh
20 Chambers St,
Edinburgh, Scotland,
EH1 1JZ
Tel: +44 (0)131 650 2341
______________________________________









______________________________________
Geoff Lee <email@hidden>
Computing Support
School of Arts, Culture and Environment
University of Edinburgh
20 Chambers St,
Edinburgh, Scotland,
EH1 1JZ
Tel: +44 (0)131 650 2341
______________________________________









______________________________________
Geoff Lee <email@hidden>
Computing Support
School of Arts, Culture and Environment
University of Edinburgh
20 Chambers St,
Edinburgh, Scotland,
EH1 1JZ
Tel: +44 (0)131 650 2341
______________________________________






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