max persistance time?

[Joseph Mack NA3T]

On Thu, 31 Aug 2006, Joseph T. Duncan wrote:

> 2 bad things can happen..
>
> applications can be running full bore (think long batch 
> type jobs.. and use a 100% of a cpu,

:-(

> last write wins..

:-(

> hopefully the keepalive settings will mitigate this ;)

mitigate, but it's not going to solve it. All clients with a 
dirty disconnect are going to leave a 100% CPU unattached 
job. The keepalives are only going to keep alive the 
sessions with a clean disconnect.

>> Can you differentiate the sessions you don't want from 
>> the ones that you want to stay idle?

> not really.. on campus we have some wireless labs and 
> wireless access that are behind a nat-proxy.

OK

> also I dont know how to test for an idle connection on the 
> director...

not much hope there unless you can do L7 (I don't know what 
L7 will look for, the absence of a clean disconnect?). 
However as Malcom says in the L7 section of the HOWTO, L7 
should be done by the application, that's what the 
application is for.

> there is a windows management tool that reports idle time 
> but I am not aware of mib/snmp way to export that 
> information

so you have two problems

o keeping up idle (or backgrounded) sessions that arise from 
a clean disconnect. You should be able to keep these open 
for any large time (eg weeks) if they aren't using any 
significant resources.

o killing 100% CPU sessions from a dirty disconnect.

does the application know whether the client has done a 
clean disconnect or not? I assume no or else you wouldn't be 
posting at all.

What does the app vendor say about this problem?

How do you handle the problem when there is no LVS?

> I could make the active but idle timeout on the real 
> servers much lower. but that would lead to unhappy 
> proffessors that leave themselfs logged in overnight on 
> weekdays.

I leave some of my xterms open for months. A professor 
should be able to do the same thing.

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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