PARDA proposes some very interesting technology, managed by the hypervisor. In the simplest terms, PARDA introduces distributed resource scheduler (DRS) for the I/O subsystem. PARDA is a software logic that manages access to disk systems without assistance from the disk controller in a fair access manner for a distributed environment. PARDA is explained in great detail in this VMware whitepaper.
This is an extremely interesting topic, as beyond the Nexus 1000V, disk systems are the next frontier to enhance in most virtual environments. PARDA’s key premise is to provide optimization and prioritization on disk systems that do not offer granular prioritization. PARDA has all of the inklings of traditional DRS – the concept of shares, awareness of multiple hosts and mathematical equations. PARDA also seeks to calculate the I/O managed per host when going to the same disk system. PARDA then works between the hosts to bring disk performance to a managed state where administrators can prioritize based on operational requirements.
Not all virtualized environments would necessarily benefit from this, however. Environments with larger storage systems that include advanced management and prioritization within the storage system may be able to provide elements of this functionality. These disk systems can generally assign greater priority and performance per logical unit number (LUN) or on selected fibre channel interfaces – but generally not by a specific VM within a LUN, mixed with other VMs of lesser priority.
I think this is the gateway to a new set of functionality for virtual environments. Check out the PARDA whitepaper and drop me a line with your take on this next-generation disk management concept.
Posted by Rick Vanover on 03/05/2009 at 12:47 PM
More Tech Library