Named Instance timeout problem

I am running two large applications on a 4 cpu SQL server with 2 named insta
nces.
There are times when I am running a query on one named instance that users o
n the other instance are getting time out errors. I am trying to justify gi
ving each instance limits on which cpu's they can use and also potentially m
emory. I tried giving the
more critical application 3 cpu's and the other one cpu. There was still a
similar problem on the critical app when running a intensive query on the ot
her which was just allocated one cpu. My boss insisted that I change both b
ack to sharing all cpu's.
My argument is that if both can hog all 4 cpu's, I can guarantee that there
will be a problem.
When the large queries are running, the HD lights are on constant and the CP
U's are all pegged at 100%. The databases for each application are stored o
n their own mirrored HD.
I was wondering if anyone out there has experienced a similar problem and wo
ndering where to go from here.
Thank You,
EverettWe went with defaults when the instance was installed. I think both are
dynamic.
"Vikram Jayaram [MS]" wrote:

> What about memory allocation? Are both instnaces alloted to have Dynamic
> Memory? In that case one instnace could be hogging system memory and not
> granting the other enough, on time.
> Vikram Jayaram
> Microsoft, SQL Server
> This posting is provided "AS IS" with no warranties, and confers no rights
.
> Subscribe to MSDN & use http://msdn.microsoft.com/newsgroups.
>
>|||Right then., Try alloting one of those to fixed memory of a lesser amount
and see if the behaviour still exists. Worth a try!
Vikram Jayaram
Microsoft, SQL Server
This posting is provided "AS IS" with no warranties, and confers no rights.
Subscribe to MSDN & use http://msdn.microsoft.com/newsgroups.