We have a PS6100 SAN and we are running into some issues with in-use space. 

I have read all about how the SAN writes in blocks and once a block is dirty it can no longer be seen as available space.  I also know that even though the space may not show available on the SAN as long as the VMware OS has available space it should not cause a problem. 

It seems that since our software provider re-configured their db maintenance and setup a local backup to the servers D drive which we have since removed (the backup portion) continues to increase the SAN volume in-use space by 10% every weeks since.  We have increased almost 300 gig in 3 weeks.  However the VM OS shows we are only using 180gig of 499.  My concern is what will happen once the in-use space gets to 100%?  I know we can keep extending the volume but we don't really want to keep doing that either.  We are also replicating replicas to a partner at our DR site.  Is there a way to keep the in-use space from increasing?

Thanks for any and all responses.