Hi,
Must agree with Tim in that performance bottlenecks are complex things to
track down, and others have all made valid suggestions regarding Indexes
etc . However I have noticed that you say ALL your files are T30 (i.e
Dynamic). Why ?, Dynamic files carry an overhead with UniVerse and at the
operating system level, which must be weighed against the maintenance time
you have.
Firstly Dynamic Files use two Unix Inodes, i.e Two File Handles to open
each Dynamic File the DATA.30 and OVER.30 sections. This means it uses two
slots in the rotating file pool (Have you checked what MFILES is set to in
your UniVerse Config as this controls the size of the rotating file pool).
The header information controlling splits and merges for Dynamic Files is
controlled by ONE UniVerse Semaphore and ONE shared memory structure (The
size of which is defined by T30FILES). This means that the more T30FILES
you have, it means more file handles and potential more collisions on the
Dynamic file semaphore (have you looked at smat -s to see the collision and
retry rate on the Dynamic File Semaphore).
Don't get me wrong Dynamic Files have there uses, but they are NOT
maintenance free (as some people think) they are low maintenance. Files
that do not increase in size or their increase can be predicted over a
given period , in my view, should not be Dynamic (why use two file handles,
where one will do). Also Dynamic Files are great for work files as they
shrink and grow with use .... BUT the time hit is when the file has to grow
again, for your temporary / work files have you considered using a minimum
modulus to control the contraction of the file and hence making sure
UniVerse does not need to repeat work it's already done. Finally, Dynamic
Files never return there unused OVER30 space back to the machine, hence
from time to time during maintenance you may wish to run RESIZE file * * *
as this has the side effect on Dynamic Files of claiming back unused space.
Hopefully, this will show you what everyone has meant by eliminating
bottlenecks is a complex recursive process, I mean I've done 3 paragraphs
on Dynamic Files alone .....
Regards,
Jonathan Smith
IBM Certified Solutions Expert
Advanced Support Engineer - U2 Advanced Technical Support
IBM Data Management Solutions
Support Phone 0800 773 771
Support Mailto:[EMAIL PROTECTED]
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