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Message Posted: Mon, 13 Nov 2000 @ 15:45:54 GMT





     
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Subj:   Re: Experiences with the Priority Scheduler?
 
From:   Claudio De Luca



Some explain about I/O troubles :

Sometime when you are doing several big insert select or join (and you can see many wait I/O with the unix sar command), with schtool you see that only one partition is working ! the system seem to be hang for the other users (schtool is very interresting to see which performance group is consuming the system)

2 possible actions :

- decrease the weight of the partition

- change the policy of the allocation group

the first action is the best but if it doesn't work, you have to change the policy !

I've have observed that change the weight of the allocation is dangerous if you are not logical with the priority.

for instance : in the same partition if the weight of your $L is higher than $H, you risk to have a system hang for everybody -> system 100% idle (it had occured seval times before we understand it !)

DE LUCA CLAUDIO
OSD





     
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