I'd recommend that you open a service request with support. Be sure to include which code version is currently running, there may have been fixes in the latest releases (but I'm not aware of any issues like this). I notice that it appears to be the Reads that are dropping, have you checked at the hosts are not performing any activity at those times? Also, please include the types of hosts that are experiencing this issue - what OS, applications, each. Also, get a new Data Collect just after (say about 5 minutes after a drop) you see the drop. We'll also need a couple of the performance archives - see KB 491175 for additonal information about collecting the data needed for a performance review.

glen

Which code level is it ?

I'm not seeing this in 4.1.1 and 4.1.2

It's 4.2.1.9535982, the last target I think.

Maybe the cron jobs are not wrongly niced. Did you raise a SR for that issue ?

There are a couple of things that "might" be causing this, but it would be best that you open a case with support.

Glen

Did you open a service request with EMC support. If so, what is the SR number - I'd like to track this.

glen