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Making
Sense of Storage Virtualization
continued
from Article Page 1,
2, 3,
4, 5
A NEW DEVELOPMENT:
TAPE DEVICE VIRTUALIZATION
The virtualization of tape devices,
or tape pooling, is an exciting
development that customers with robust tape
storage requirements are looking at today.
Tape virtualization allows a host
application to access a logical tape drive while
the virtualizer actually accesses the
physical tape drives. Since the biggest
bottle-neck in disk-to-tape operations is
writing the data to tape, virtualization
at
the tape device level provides the
ability to have one logical tape presented to
the host with any number of physical
drives on the back end. As a result,
performance improvement in a portion of the
connected physical drives can be achieved
over a single drive by eliminating
the management issues associated with
multiple tape drives on individual hosts.
Other features include the ability to
configure tape drives in a RAIT5
configuration, which provides protection
from faulty tapes. In addition, the
tape virtualizer can facilitate the
sharing of physical tapes between hosts and
applications without the cost or overhead
associated with added software. Of even
greater significance is the
virtualizer’s ability to represent tape drive
technologies as something other than what they
are making a 9840 drive appear as a
DLT drive if an application doesn’t
sup-port 9840 as an example. The
application will perceive the drive as a DLT
drive but the data would physically be
written to a 9840 drive. To further support tape
virtualization, new functionality called tape
multicasting will allow an application to write to
a logical tape drive with the
virtualizer writing the data to multiple tape
drives on the back end. For example, if a
customer is currently running two backups
serially—one for onsite and one for
off-site— tape multicasting could essentially
allow the same customer to run these
two backups simultaneously with the
same result.
Mike Hogan is a storage consulting practice
manager at Imation. Robert A. Jackson, Erik
Johannessen, Rich Mikulak, Matt Reller, and
Jeff White are senior storage engineers at
Imation (Oakdale, MN).
Reprinted by permission from the publisher of the
Volume 6, Issue 3 edition of Storage Management
Solutions.
©2001 West World Productions, Inc.
Authors’ note: This
article, one in a continuing "From
The Lab" series, is based generally on
consulting and testing experiences from Imation’s
Storage Networking Lab, in Oakdale, MN.
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