Parallel Access Volume (PAV) allow you on System z to have more than one I/O outstanding per volume. However it’s not so easy to set up and maintain, so this is why there is HiperPAV, which is quite easy to install and maintain. And it’s supported by all in service Linux distributions now.
The white paper is gone from the IBM site – so the link is no longer working.
The new white paper / howto “HyperPAV setup with z/VM and Red Hat Linux on zSeries” describes the step by step setup for HyperPAV for z/VM and zLinux. So if you are using ECKD disks and have any I/O performance problems – make sure you’ve implemented this.
As this white paper is removed – here are a few pointers to get you started:
The presentation “z/VM PAV and HyperPAV Support” and the z/VM HyperPAV web page has a good overview from the z/VM side and the presentation “HyperPAV and Large Volume Support for Linux on System z” shows the Linux part (which is basically working out of the box). And there is of course the Virtualization Workbook, which covers HyperPAV as well.
The whitepaper has been removed from the IBM site – (updated 05/30/2015)