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DISASTER
RECOVERY
_____________ Corporate President/CEO Vice
President
CONFERENCE REGISTRAR Brazil:
Jose Carlos Ferreira
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Click Here for a Printable Version STORAGE ISSUES Enhance
Tape Backup Systems To Keep Pace With Server Capacity, 24x7 Network
Access By DAVID J.
DEMLOW These are realities
for data backup: 1) For business generations, tape backup was sufficient;
2) tape backup capabilities have not kept pace as 24x7 demand for data
access has soared and the overhead burden of backing up higher-capacity
servers has multiplied; and 3) continuous-replication technologies that
enhance tape backup now offer efficient solutions to this dilemma. Enhancing the backup
process by continuously replicating critical data to centralized servers
means tape backup systems can back-up the disk-based replicas, rather
than obliging administrators to go through the effort of backing up
from production servers, a system-clogging, bandwidth-hogging process.
Meantime, tape backup retains its priority function as an archival medium,
retaining its investment value. IT professionals found
their corporate voice during the Y2K run-up, earning a seat at the strategy
table in enterprises around the globe. From that elevated perspective,
they now should help those business-unit peers snap out of an apparently
widespread post-Y2K complacency about this looming backup quandary.
Corporate executives have the fiduciary responsibility to protect a
company’s assets, especially data, leaving IT professions charged
with the responsibility of enlightening them about the continuous-replication
option as a pragmatic way to update readiness and accommodate the daily
business realities of increased access demand and more muscular server
capabilities. The Closing
Window Such traditional backup solutions,
obviously, left at least a day’s worth of data unprotected from
a server or disk crash, with rebuilding the server from tape taking
many hours to days. Access and recovery gaps widen further with weekly
backups or combination strategies of weekly full backups with incremental
or differential backups run daily. Such data loss and recovery delay
was acceptable for many companies, but competitive pressures and increased
data load on corporate networks now make it increasingly less acceptable.
Recreating word-processing documents or spreadsheets still may be acceptable,
but losing a day’s worth (or more) of productivity of a software-programming
team, for example, is probably seen as financially and developmentally
too expensive. The typical backup window has been
inexorably closing. Evolutionary business-process changes, accelerated
by Internet-based communications, mean distributed employees, partners
and customers are logging into servers and databases globally 24x7.
E-commerce enterprises require always-on systems and continuous data
protection for order processing. Even a delay of e-mail, now generally
considered “mission critical” at most companies, can severely
impede the ability of a company to operate. More complicating, however, is
that tape-backup technology – despite increases in megabytes-per-minute
speed – has not kept up with the growth in server size, causing
total restoration times to continue to increase. Not so long ago, a
typical 50-gigabyte server could be restored in about eight hours at
a rate of around 10 MB/min with traditional tape-backup technology –
if everything worked well. For a one-terabyte server today, restoration
at a 900 MB/min or 52 GB/hour rate will take 19 hours, even with the
best tape-backup available – during which time the server and application
would be unavailable to users (and potentially a threat to service level
agreements (SLA) delivery). Opening
The Window Continuous replication can be performed
at either the file level (replication) or at the disk or disk block
level (mirroring). Unlike traditional tape back-up, file-based replication
uses the smallest amount of network bandwidth possible because it captures
and transmits only the changes made, rather than sending the entire
file across the network each time. By contrast, disk mirroring (usually
operating in a synchronous mode) maintains a replica of databases and/or
file systems by capturing and transmitting changes at an entire disk
block level. Its synchronous nature also delays the I/O process of the
primary server to accommodate the update of the remote site. The big advantage of asynchronous
replication is that it significantly reduces the need for network bandwidth,
particularly for large files like databases, video captures and activity
logs. Because file replication software is flexible, users have the
option of selecting for continuous replication just those files or directories
they deem mission critical, typically only five to 10 percent of total
data. This greatly trims the cost of off-site protection, compared with
mirroring applications. The elegant beauty of continuous
replication is it allows a consistent copy of an application environment
to be accessed by software utilities (or other applications) while the
production copy stays online. The dedicated high-availability (or disaster-recovery)
server can be accessed even if the production server is down. Every
file on the target server, regardless of its state on the source, is
closed and available for backup at any time. Changes to a file are queued
on the target until backup is completed, then automatically applied.
Moving the backup process to the secondary server has zero impact on
production-server performance and generates no additional network traffic. As an affordable, scalable and
easily managed option for enhancing tape backup systems, disk-based
continuous replication technologies can provide both “instant”
protection and fast recovery via on-line disk. Tape backup then maintains
archival, point-in-time copies of different file versions for the record.
And continuous replication facilitates a variety of critical business
needs, including high-availability and failover capability, disaster
recovery, Web-content replication, data distribution among multiple
servers, platform migration, and change management and testing. IT Challenge “Apathy appears to play a
much greater role in the general lack of readiness than most industry
professionals are willing to admit,” according to a post-Y2K Gartner
Group study. Failing to embrace a rapid-recovery capability that enhances
tape backup, the study concluded, is “like playing Russian roulette
with the enterprise.” The Gartner Group study said most
IT managers publicly support the criticality of business continuance,
but reported that apathy set in when budgets started tightening and
there were no recent catastrophic failures. Turnover of IT personnel
often relegated business continuance to a second-rate problem for “my
successor” to deal with, echoing arguments in the mid-to-late 1990s
for delaying Y2K renovations. “If they don’t feel the pain,”
one Gartner Group symposium exhibitor said, “they won’t buy
the cure.” “Like any form of insurance,”
the Gartner Group report said, “the decision ultimately boils down
to risk evaluation and how much is acceptable to the leadership.”
Cost is no longer a viable excuse, as there are many products that focus
on the vulnerable server-based environments that are amazingly cost-effective
to acquire and deploy. Considering that most of the outages occur with
these distributed platforms, protecting your enterprise has never been
less expensive. “Many IT managers place data
recovery and business continuance planning in the same category as buying
insurance for the company car. ‘Buy as little as possible and keep
the expense to a minimum – we’re never going to need it anyway.’
This can be a dangerous approach. With instantaneous online and Web-based
transactions driving real-time revenue, any IT manager not prepared
to recover mission-critical systems is risking not only their career,
but potentially the survival of the enterprise. Such behavior is nothing
short of fiduciary malpractice.” David J. Demlow, vice president of product management, joined NSI Software in March 1997. He is responsible for defining the company’s impressive product roadmap and positioning. This includes identifying market opportunities and requirements from existing and potential customers, performing competitive analysis and monitoring overall industry trends and events. Demlow has more than 10 years of product marketing and management experience in the networking and storage industry. To comment on this article, go to 1503-18 at www.drj.com/feedback.
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