e i g h t - c u b e d . c o m 

Single member shadow sets

Bob Gezelter has just published an article on openvms.org concerning, among other things, the proposal that HP change the licensing terms for Host Based Volume Shadowing to allow no-cost single member shadow sets.

I wholeheartedly support this proposal. HBVS is to my mind a critical component of redundant and resiliant systems, and reducing the barrier to entry can only be a good thing for customers and HP both.

The benefit to the customer is the ease of adding or transitioning storage with the purchase of the HBVS license to enable more than one physical member. If the single physical device to be transitioned is already a member of a shadowset, no downtime need result.

This concept is so useful that even at the last large site I worked at that had a full license for HBVS, we still had every disk respresented by a DSA device, even if they were a single physical disk. The time saved by being able to add and remove shadow members to copy/transition is worth the extra layer of driver code.