Kbase 21464: Checking Read / Write Ratio on Your Database
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
8/8/2006 |
|
Status: Unverified
GOAL:
Checking Read / Write Ratio on Your Database
GOAL:
The Read and Write Ratio
FIX:
You can use the PROMON utility or the Virtual System Tables (VST) to gather information on how well things are going during the execution of an application.
Record read:write ratio = (RecReads) vs. (RecCreates) + (RecWrites) + (RecDeletes).
The goal for GUI Applications with SmartObjects is: < 50:1.
The goal for CHUI Applications is: < 10:1.
NOTE: Higher ratios of 100, 150:1 can be problematic.
Make samples for large times, but watch for spikes in rate, especially in small installations. To retrieve the heaviest user information use Promon R&D / 3 / 2. This will show you the I/O rate by process. The same information can be found in the VST _UserIO. If you find a user with a rate higher than normal, check what the users were running. The advantage of using the VSTs instead of PROMON is that you can sort the results and can have on a GUI front-end.
Other Startup Parameters that are turned off by default in Version 9 but directly affect the VSTs are:
_tablestat (VST)
-basetable/-tablerangesize in Version 9
-tablebase/-tablelimit in Version 8.3
These parameters might cause a slight performance hit because there are writes to the VST. Watch for very fast read rates and more records returned than appropriate. Check suspicious code in isolation. Use this information to separate data into storage areas. There is no point to read more data than there is in a table. Be careful with reporting tools and report printouts which will considerably increase the READ:WRITE Ratio.
FIX:
References to Written Documentation:
Progress Solutions:
19450, "Tracing Operations Per Table: VST's _tablestat _indexstat"