FOCUS STORAGE
Issue 6, Oct/Nov 2009
CUTTING THE POWER OF STORAGE Policy based storage allocation will save power in the long run but most systems are not ready for it
characteristics, and Flash does not have a long runway, believes Barry Whyte of the SAN virtualisation architecture and development systems group at IBM.
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IBM is developing “Racetrack” storage, where data is stored magnetically on silicon nanowires with retrieval governed by “massless motion”. In short, no moving parts and vastly reduced power needs, meaning the amount of energy needed to store, retrieve and back up your data will fall inexorably.
Racetrack is for the future. But ask about power and cooling efficiency of the storage boxes and you are quickly sidetracked down the traditional routes of data management with some spin-down capabilities.
EXPANDING NEEDS There are efficiencies to be had in migrating your data from Flash to Tape via HDD as efficiently as possible (within the needs of the application – and therefore the business). But dynamic provisioning is not ubiquitous.
Whyte says: “Policy-based placement that can migrate data automatically, abstracting to spare capacity – thus allowing you to power down disks…That is the next step.”
There already exists the capability to manage storage separately from the server in a form “where the server does not know or care where the data is stored”, he says.
This level of virtualisation is available to mid- range storage systems to raise utilisation and management across hardware from different vendors and is delivering efficiencies. But in the world of storage, nothing stands still. And often, that is part of the problem. All those spinning disks are drawing power, and despite spin-down technologies, the policy-based allocation – which is significantly cutting storage power draw – has yet to arrive.
If you develop a policy-based approach and then find the software that will do it for you, one day you will be able to dictate which media are holding your data. You will then be able to dynamically move your data to maximise disk
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utilisation and power down those disks that are not being used. A variation of this was once called Information Lifecycle Management – it was touted heavily but faded away. It might make a comeback under the guise of power management.
MORE TIERS Dr Mike McCaig of Bull Information Systems encourages the implementation of a tiered storage design – keeping data on the right media for its required use, as an operational energy saving action. He says larger disk drives with slower operating speeds use less energy than small high-speed (high IO-rate) drives.
High-capacity, low-power SATA drives produce a carbon footprint that can be less than 10 per cent of high-speed enterprise class drives. Tapes and virtualised tape libraries are also among the most energy efficient means of providing storage for backup.
A review of the organisation’s data retention policy and information lifecycle management approach may reveal where data center online capacity could be replaced with offline storage. Similarly, reviewing backup policies and utilising deduplication technology will reduce the total work performed in backup
systems and reduce the volume of data being stored at any time. (see box, page 43).
Estimates of power savings from the use of thin provisioning range widely (from 10 per cent to more than 75 per cent) and like any other energy efficiency initiative are determined by a number of operating factors. Assuming an energy consumption of 100W/ TB, a data center operation running 10TB of storage and achieving a 40 per cent saving from thin provisioning would save 0.4KW/h, says McCaig.
With the improvement in storage products, energy performance and capacity each year, simply eliminating old technology is an obvious step towards reducing power consumption. Today’s latest drives deliver more than 20TB/kW – that is more than doubling what was available five years ago.
Great inroads have been made in making caches bigger (for performance), deduplicating data and thin provisioning (to save capacity, see box page 43) and virtualisation (for management). The latest generation of disk subsystems have features such as policy based spin-down and adaptive cooling designed in to them in a bid to become more energy efficient.
lash technology will be superseded within a decade. There are many competing storage formats in development, each with their own
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