Vdbench and Data Validation against very large luns or files
By Henk Vandenbergh-Oracle on Feb 27, 2009
One warning, something that some people have run into without knowing it:
If your luns are very large and your xfersize relatively small and your iops relatively small, then it may take quite a while before a data block is accessed for the second time, and therefore being read and its data validated.
For instance, with a one TB lun using an xfersize of 8k at 100 iops it will take 37282 hours or almost 5 years before each block is accessed ONCE.
You can make the lun look smaller by using the size= parameter
sd=sd1,lun=/dev/rdsk/cxtxdxsx,size=5g (Vdbench then only uses the first 5gb of the lun)
or you can use the 'range= parameter:
sd=sd1,lun=/dev/rdsk/cxtxdxsx,range=(50,60) (Vdbench now only uses the space between the 50 and 60 percentile of the lun's size)