Green storage best practices control costs, increase energy efficiency
By James Damoulakis
By implementing the following green
storage best practices, firms can use a mixture of technologies and tactics to control data
center power and cooling costs and increase
their storage energy efficiency.
- Avoid overspending and overprovisioning.
It's obvious that spinning disk is the source of most storage
power consumption, and unused spinning disk represents wasted energy. But there are several
challenges in growing storage incrementally, including the organization's ability to accurately
forecast storage capacity needs. Beyond capacity
planning, it requires a relationship with a vendor who can support the incremental storage
growth. The technology must also allow the storage to expand easily and with minimal disruption.
- Revisit your tiering strategy.
Small, fast disks demand more energy than large, slow disks, so the distribution of data across
various storage tiers can have a big impact on your power consumption. A study by EMC Corp. last
year indicated that storing a terabyte of data on a 7,200 rpm 1 TB SATA drive is 94% more efficient
than storing it on a 15,000 rpm 73 GB Fibre Channel (FC) drive. This provides an added incentive to
ensure that storage service levels and tiers are properly aligned based on application and data
value.
There are many situations where tiered storage
allocations are far from ideally distributed. Understanding this distribution and developing a
clearly defined set of service-level requirements to apply to new and existing applications can
lead to substantial savings in equipment cost and energy use.
- Revisit RAID policies.
Another facet of a tiered storage strategy is the RAID
data protection policy applied to a given tier of storage. It's not so prevalent these days, but
overprovisioning of RAID 1 or RAID 10 increases the number of spindles and power consumption. When
additional performance or availability isn't required, the drive count can be reduced.
- Consolidate storage arrays.
The more frames in a data center, the more power that needs to be reserved for them. Older arrays
tend to be less efficient than the latest models, so reducing the number of storage systems is an
obvious option, just as consolidating physical servers through virtualization is. Newer
virtualization arrays may also offer enhanced functionality such as thin
provisioning to improve utilization and further reduce energy consumption.
- Establish power usage metrics.
Power specifications typically enter a storage infrastructure discussion only during installation
planning. However, to truly align data center and IT infrastructure objectives, this will need to
occur. Organizations like The Green Grid promote
standardized data center efficiency metrics. It will also become necessary to establish metrics
such as GB/kW or IOPS/kW, and to then determine these rates for each tier of storage as well as
usage for the storage infrastructure in total.
- Consider solid-state drives (SSDs).
While solid-state
drives (SSDs) are still a new phenomenon for many, they can play a role in replacing
power-hungry, high-speed, low-capacity disks. In addition to offering higher performance, EMC
reports that on a per-IOPS basis, flash disks require 98% less energy. It's therefore imperative
that organizations do their homework and understand actual performance requirements before making
any substantial investment in this technology.
- Consider massive array of idle disks (MAID).
At the other end of the performance spectrum is MAID
technology. We know a significant amount of data currently stored on spinning disk is accessed
infrequently. From an energy-consumption standpoint, the most efficient disks are the ones that
aren't spinning at all, which is the rationale behind MAID. For archival data that still requires
accessibility, this technology represents an attractive alternative to conventional, continuously
spinning, nearline storage.
- Make energy usage a buying consideration.
As the demand for green
storage grows, vendors have realized that energy efficiency can be a competitive
differentiator. It makes sense to factor this into equipment purchasing criteria, and to consider
energy impact when architecting new storage infrastructures. Often times, the focus is on capital
expenditures (CAPEX) and insufficient attention is paid to operation expenditures (OPEX). However,
evidence is mounting in the server world that these lifecycle costs, including power and cooling,
can actually overshadow CAPEX.
24 Jun 2009