Storage Virtualization Can Reduce the Cost of Maintenance
by David Merrill on May 3, 2012
This is the first in a series of blogs that discusses the impact of enterprise, controller-based virtualization and the impact to secondary costs. By secondary costs, I mean costs that are not usually and obviously measured with virtualization initiatives. In this entry, I will outline the impact of storage virtualization to array hardware maintenance.
Hardware maintenance is the recurring monthly cost that emerges after the warranty period is over. HW maintenance ensures that vendors will continue to support and repair equipment according to services and response levels. Hardware maintenance is not absolutely required, but without it an IT shop will run the risk of outage or scheduled downtime to resolve (inevitable) machine faults and failure (see 2nd law of thermodynamics – the laws of entropy).
Storage virtualization can have an impact on the total cost of storage HW maintenance in 4 different veins:
1. Virtual assets can now be demoted (or promoted) based on age, performance levels and related maintenance costs associated with the array. Other arrays that are still required for capacity, but have substantial maintenance costs, can be demoted to a lower tier of service. In that demotion of tiers, there should also be a demotion of service levels; therefore the maintenance rate or service level can be significantly lowered.
I know of customers that keep assets a little longer than usual (since they are fully depreciated) but assign them to lower tiers of service. They will significantly lower the maintenance levels from the vendor or in some cases drop maintenance entirely and go to a T&M arrangement for break/fix. I have also seen customers purchase some spare trays and perform their own replacement in the case of failure.
Remember that with virtualization, the subordinate arrays inherit the attributes and capabilities of the parent (controller array), so the software and management functions performed with a virtual pool of capacity is born by the virtualization controller.
2. Virtualization usually produces large rates of consolidation and reclamation of capacity (especially when virtualization is bundled with over-provisioning and ZPR). In these cases large rates of reclamation are often seen, and so the macro capacity can be arranged to retire the older arrays that have high maintenance costs. The total virtual capacity is the same, but the frame count is reduced. We always get excited about the environmental impact of frame reductions, but there is an important maintenance cost that can go down with these actions as well.
3. When heterogeneous, controller-based storage virtualization is employed, the procurement department often has the leverage to pit vendor against vendor to secure the most favorable maintenance costs. Many of the older arrays (that require month to month maintenance) can be commoditized within the virtual environment. As a commodity, procurement now can leverage the vendors to negotiate the most favorable rates. The winner stays on board in the virtual pool; the loser gets shown the door.
4. Controller- based virtualization can have a significant impact on the time and cost of array-based migration. This migration is expensive ($7-10,000/TB). A good portion of the migration cost is related to overlapping HW (and SW) maintenance costs. By shortening the migration timeframe, HW maintenance costs will drop. See this paper on more details of the costs of migration, including maintenance.
Maintenance can be a significant part of the storage TCO, especially if the assets are older or are intended to be used for a longer period of time. Maintenance, as a percent of TCO, can often be 20-25% of storage TCO. Virtualization can be a powerful ally to reduce and tame these costs, while helping to sweat the assets and improve ROA over time.
