You wouldn't buy a Porsche just to go grocery shopping, and you
wouldn't top off the gas tank just for a spin across town. However,
storage professionals overbuy both performance and capacity in an
effort to forestall potential storage problems.
Tiered storage is one way to address this
problem -- matching storage resources and costs with the value
of data. Today, storage is poised to build on this notion with
application-aware storage, using business
policies to bring autonomy and intelligence to enterprise
storage. Still, there is a great deal of confusion surrounding
this technology, its capabilities and its deployment. This
article considers the main ideas of application-aware storage,
its benefits and limitations, and examines typical deployments.
What is application-aware storage?
At the highest level, application-aware storage should recognize
an application and be able to enhance its storage performance by
improving the relationship between storage and applications --
often manipulating characteristics, such as data layouts, caching
behaviors and
quality of service (QoS) levels. While some
storage platforms may be tailored to application-aware storage
tasks, it is more common to see software tools imposed on top of
existing disk storage resources.
However, a more precise definition is elusive because
application-aware storage is not a single product or technology.
This leaves a lot of room for marketing hype, multiple meanings and
interpretation. "The definition lies in the eyes of the beholder,"
says Greg Schulz, senior analyst and founder of the StorageIO Group
in Stillwater, Minn.
Application-aware storage can mean content awareness -- using
APIs to tailor a storage system, such as an EMC Corp. Centera, for
certain applications. However, the most common definition of
application-aware storage today is strongly reminiscent of storage
management -- using storage, storage systems or storage management
tools to support policies, allocation, configuration and use --
based on application use or service requirements and profiles.
"What this [application-aware storage] brings is better visibility
to where the applications map to the storage resources," says John
Merryman, principal consultant, data classification services at
GlassHouse Technologies Inc. in Framingham, Mass.
In this context, application-aware storage presents a new
"policy management" dimension to tiered storage where
application-aware tools can use policies and business rules to
automate the assignment of storage for specific applications. For
example, messages and data generated by an email server may be
mapped off to midperformance drives running RAID 5, while data
produced by a backup application may be sent to storage provisioned
at high-capacity SATA disks in a RAID 6 group. As another example,
Oracle data could be sent directly to a high-performance Fibre
Channel storage area network (SAN).
What are the benefits and drawbacks to application-aware
storage?
Conceptually, application-aware storage is intended to improve
storage performance and storage service delivery and automate some
of the manual provisioning processes that have routinely demanded
IT knowledge. The challenge is to establish a tangible relationship
between the storage, the applications and the business policies.
Storage professionals could then see those relationships and tailor
them, allowing tools to make higher level decisions about storage
provisioning. When properly deployed, a storage administrator
doesn't need to worry about where an application is storing its
data -- tools will make those decisions and distribute data
accordingly to the proper storage platform, storage tier and LUN.
Experts note that such capability will be increasingly important as
storage resources proliferate and become more complex.
"Institutional knowledge is deteriorating," Merryman says. "So
having the technology to gain these insights is important."
There are numerous vendors today providing management software
tools with "application-awareness" features. Software vendors
include SANscreen from Onaro Inc., WysDM for Fileservers from WysDM
Software Inc., StorageConsole from Aptare Inc., the Virtual
Recovery Engine from Illuminator Inc., Veritas Storage Foundation
from Symantec Corp., BalancePoint from Akorri Inc. and StorageGRID
from Bycast Inc., among others. On the hardware side, experts point
to EMC Corp.'s Centera CAS system, Hitachi Data Systems' Archivas
platform and the Assureon archiving platform from Nexsan
Technologies Inc. as examples of application-aware storage for
archiving purposes.
The problem with application-aware storage is that practical
products are still in the early stages of development and
deployment. It's a technology that is really only suitable for
large storage organizations, so it's still considered to be a niche
feature. "Like any technology, the early adopters are paying the
price to understand the value proposition," Merryman says. "It's
probably not going to be the silver bullet to cure all tiering and
[storage] efficiency woes."
Consequently, application-aware storage deployments can often be
marred by unrealistic expectations of the technology. Tools still
need to be deployed, configured, tailored and tweaked. Experts say
it's important to evaluate and compare tools very carefully prior
to deployment -- a pilot program can reveal many potential
problems. "Define your requirements and lead with that," Merryman
says. "Don't look at the vendor .pdfs or let that drive your
requirements." Understand any interoperability problems, procedural
changes, management overhead and scalability issues that present
problems after installation.
How do you deploy application-aware storage?
Generally speaking, application-aware storage is a policy
manager implemented as a software layer installed on top of
storage, and on top of storage management utilities. The policy
manager extracts the established technical rules and business
policies necessary to make rudimentary decisions. "A policy manager
is no good unless it's got good, viable rules and information to
act upon those rules," Schulz says. "This allows the policy manager
[application-aware storage software] to act upon those rules."
Once installed and configured, the application-aware storage
software should operate with virtually any storage platform in the
enterprise. Experts emphasize that any storage system has the
potential to be "application aware." Still, it's important to
verify interoperability with your current storage systems and
existing storage management tools before fully committing to an
application-aware storage product.
Also, you can employ purpose-built storage hardware to form the
foundation of an application-aware storage infrastructure. For
example, the Sun 5800 requires WebDAV or an API to access the data
objects that are stored on its disks, thus mating the accessing
application to the storage system. Similarly, EMC's Centera relies
on the use of APIs that tie directly to the applications.- Some
experts refer to this as "application-affinity" or
"application-affiliated" storage. "You just can't mount a volume
with NFS, and sit reading and writing the files," Schulz says.
Remember that application-aware storage is typically intended to
merge technical and business practices, so implementation cannot be
an IT-only process. Successful deployment must involve
participation from throughout the organization to understand the
importance of applications, the data that applications produce and
the optimum rules/policies for storing that data -- a process
similar to data classification.
Metadata also has a role to play in application-aware storage,
using details about various data types to feed the policy managers
that make decisions about where and how that data is stored.
However, it's important to note that this technology relies on very
different details than the metadata used in traditional indexing or
e-discovery searches. A CMDB (configuration management database)
provides metadata details about the systems, applications and their
configuration, rather than details about the application's data.
"You're dealing with infrastructure resource management (IRM) --
managing the resources to deliver IT services," Schulz says.
What is the future of application-aware storage?
Application-aware storage is certainly not a new idea. It has
been mentioned as far back as 2003 and earlier, but has only
recently started to receive attention as a unique and viable
storage technology. Experts suggest that this recent acceptance can
be traced to several factors, including an almost universal use of
SAN technology and a fundamental shift toward server and storage
virtualization to improve infrastructure efficiency, reducing the
tendency to overbuy storage to solve availability and capacity
problems.
The most notable issue is a broad lack of deployment, so experts
are still hoping to see more active rollouts of application-aware
storage tools. Beyond that, the goal is greater automation,
allowing the software to act on wider range of policies and
transparently make more autonomous decisions about storage in the
enterprise.