The Case for Managed Storage
By Randy Dufault, Principal Integration Architect
Genus Technologies, LLC
6600 France Avenue
Suite 425
Minneapolis, Minnesota 55435
tel: 952-844-2626
fax: 952-844-2670
www.genusllc.com
 2008, Genus Technologies LLC
All Rights Reserved
Content Manager on iSeries (CM) offers two levels of storage in its
storage management model: primary storage to iSeries system disk and
secondary storage to an optical library. A legacy option for secondary
storage to tape is no longer supported. Content streams – objects or
documents, if you will – are initially stored to primary storage and are
always ultimately retrieved from primary storage.
In a typical installation, depending on operational scheduling of the CM
storage management procedures, new streams entering the system are
copied from primary to secondary storage. They then remain on primary
storage for a defined period of time and are ultimately removed from
primary storage. Future access to the stream requires retrieving the item
from secondary storage back to primary storage. Streams retrieved in
this fashion remain on primary storage for just a short period of time.
CM depends on its own internal storage management model, rather than
external storage management middleware, to keep track of the potential
millions of streams that are captured into a system over time. A distinct
benefit of keeping storage management internal is that CM has complete
control over the performance and operation of the attached storage –
there is absolutely no dependence on external software.
One significant limitation of CM’s storage management model is its
inability to adapt to evolving storage technologies. Optical library
technology, while making great strides in storage density and retrieval
performance a decade ago, is now considered much too slow given the
relative low cost and high performance of today’s magnetic disk storage
systems. Add to that the maintenance issues associated with the
mechanical components inside an optical library, and it becomes readily
apparent why the storage management limitations of CM are an issue for
many of the thousands of organizations using the software.
An internal storage management strategy, while certainly very valid for
the time when CM was first deployed, required CM to be responsible for
supporting any and all new storage technologies a customer may desire
to deploy. With literally thousands of storage devices available now, and
many more being introduced each year, CM has not, and it can be
argued, could not possibly keep up.
Many CM customers are addressing the performance and maintenance
issues associated with the optical storage limitation by simply retaining
most or all of their CM content streams on primary storage. While this
strategy has proven to work, it brings with it a number of management
issues and outright problems.
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CM’s rather simplistic primary storage management model relies on
limited capacity file system directories, located in specific areas of the
iSeries file system. System administrators must constantly watch and
manage the capacity of the directories and must manually create new
directories as the repository grows. Additionally, when it becomes
necessary to move the directories out of the file system locations where
CM expects them to be, a number of complex manual link entries must
be created. With the added need to constantly alter backup processes
to account for growing disk utilization and to fit within shrinking backup
time windows, management of CM can consume a considerable amount
of system administration resources.
While the management issue may be no more than an additional
administration responsibility, two specific issues with an all primary
storage strategy have potentially significant implications. Those issues
are system recovery and disaster recovery.
Magnetic tape systems, still the most popular means of backing up
computer systems, are limited by capacity, bandwidth and server
behavior in the amount of data they can backup or restore in any given
period of time. It may be impractical to restore a large set of streams to
primary storage within a reasonable amount of time. This fact has
implications for system recovery in the event of some sort of massive
failure, implications for migration to new servers and implications for
recovery when a disaster requires that backup data facilities be used to
keep the business going.
When using an all primary storage strategy, CM will not operate properly
until the entire set of streams is restored. It is very reasonable to expect
that a system with several million stored streams may take a full day or
longer to restore, depending on the quality of the backup and other
factors. CM’s requirement that all the primary streams be available could
delay the reactivation of critical business systems for an extended period
of time.
Managed storage, leveraging capabilities like those provided by IBM’s
Tivoli Storage Manager (TSM) middleware, can reduce overall
administrative requirements for managing CM and can certainly improve
the ability to recover a CM system either in an emergency or for planned
system recovery events like a server upgrade. Paired with MBS’
StorageView™ connector for CM for iSeries, TSM, or its sister product,
the System Storage Archive Manager
(SSAM) on IBM’s System Storage DR 550 data retention appliance, can
effectively address administration and recovery issues.
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TSM, or for that matter, many other storage management software
products, provide application isolation from the actual storage hardware,
provide for real time high availability and disaster recovery mechanisms,
and manage backup and recovery processes with minimal intervention
from administrative staff. New storage technologies can be deployed
without affecting or modifying CM. Backup and disaster recovery
strategies can be modified or enhanced, again without affecting CM.
With the StorageView connector, CM’s storage management is
administered in the fashion it was intended to be, with primary storage
relegated to short-term cache needs and with secondary storage holding
the content streams. While CM reports that the content is stored on an
optical library, higher performance disk storage subsystems connected
to StorageView provide retrieval performance very near that available
with primary storage.
In the rapidly evolving storage technology market, it is impossible to
accurately predict what the hardware environment will be even in the
near future. New innovations enter the market very quickly. It is much
easier to predict what the software environment will be because of the
substantial investments businesses make in integrating middleware like
CM, with their mission critical systems. Changing software is
substantially more difficult, and more expensive, than changing
hardware.
The StorageView connector, along with storage management
middleware like TSM or SSAM, helps to isolate the application software,
which is essential to a business and cannot change quickly, from the
hardware, which can and will change quickly. New hardware can
provide substantial capability and performance improvements for an
organization as long as existing application software doesn’t limit the
ability to deploy new hardware solutions. A managed storage strategy
allows businesses to leverage storage system performance
improvements while accessing a broad range of business continuity
options. Equally important, an effective managed storage strategy
protects the long-term viability of an organization’s investment in its
Content Manager infrastructure.
Contact:
Jim Engelking, Director of Business Development
Genus Technologies, LLC
6600 France Ave. So., Suite 425
Minneapolis, MN 55435
952.844.2645
[email protected]
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