Is there a way to throttle host IO on the backend ? We have a datawarehouse that does a dump every night. Rest of the day the ios are minimal.
But during the dump, the host causes the WP pending to touch 90% thereby affecting overall symmetrix performance.
20 devices occupy almost all of the cache slots (upto 5% each) ..
There isn't any QoS that will help with this case. DCP is a perfect solution, however if the box is VP (thin), don't let the target value on the Default partition get too small. I recommend no smaller than 50% for the default. The partition you are putting these dump devices in should be small anyway, around 10% target value should work well.