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Feature
Getting backup right
Advances in technology have helped tapes retain their share
against disks in the battle for the backup market, says Vertika Yadav.
In 2004, IDC India predicted that the combined market for tape and disk had
grossed Rs 1,000 crore. The growth rate of tape and disk was projected at 1.7
percent CAGR and 9.4 percent CAGR respectively for the next five years. Although
the predicted growth rate for tapes is on the lower side, the growing popularity
and affordability of disks will not result in tapes being edged out of the secondary
storage market. “Nobody can say that tape is on its way out,” declares
Sanjit Sinha, Senior Manager, Hardware Research, IDC India. “Both disk
and tape have growth prospects for vendors, and will co-exist.”
Earlier, disk usage for backup storage was expensive, but with SATA, it has
become an economical choice. Enterprises continue to take a copy of data on
tape and use it as a low-cost disaster recovery option by sending the tapes
to an offsite location.
| What Quantum users say |
| A majority of Quantum DX product line
users indicate a reduction in the duration of backups ranging from 30-80
percent of their previously established timeframe using tape-based backup.
End-users indicate that their DX solution either prevented the creation
of or removed storage bottlenecks in their backup and recovery infrastructure.
According to Subrato Saha, Head of IT, Suraksha
Hospital, “We need faster backups and hence are using disk-to-disk
backup to shrink our backup window.” This is due to faster disk-to-disk
data transfer speeds. Generally, disk-to-disk backup shrinks backup and
retrieval time, and is 2-3 times as fast as conventional backup devices.
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Financial services, telecommunications and IT services companies have been
early adopters of disk-to-disk storage. The need for disks has been fuelled
by factors such as growth in data and new product releases based on data mining
activities. Disk gives the capacity to directly access stored data. “We
use disk-to-disk backup for databases which are quite large in size and if the
data therein requires minimal restoration time,” informs Sagar Sule, President,
Cyquator Technologies.
Traditionally, data has been backed up on tape drives and
libraries. The backup software is responsible for implementing policies on scheduling,
retention times and media management; this has worked well with small data sizes.
“Our secondary storage strategy revolves around robust data management
practices which use a combination of Veritas Enterprise NetBackup technology
with Enterprise- class LTO Technology-based tape libraries from StorageTek,”
discloses Munish Mittal, Vice- president for IT at HDFC Bank. The tape libraries
used here are automated, equipped with robotic arms and Gen II Fibre Channel-based
technology. “We continue to use DAT/DLT technology on some mainframe-class
machines like the AS400, Tandem and for operating system or file system backups
of large Sun servers,” Mittal adds. The organisation’s infrastructure
manages roughly 3 TB of data on a daily basis and close to 6 TB on month-ends.
“Tape has the advantage of being removable, and it has a shelf life of
30 years which makes it perfect for archiving,” says Jim Simon, Quantum’s
Director of Marketing for Asia Pacific.
| Information Lifecycle Management
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| ILM deals with the management of an
enterprise’s content, saving it on different levels of storage based
on its value to the enterprise as well as the needs of regulatory compliance.
It offers a viable strategy for organisations and the eventual disposal
of heaps of data. A company operates a storage system which segregates data
based on how frequently it is used, as well its regulatory storage requirements.
Risk management, operating cost concerns and compliance requirements are
increasing interest in ILM.
In India, awareness has
grown, and a number of organisations are keen to try and test these solutions.
The BFSI sector is
catching on to the concept
faster than any other because of the regulations that bind it.
“HDFC Bank is in the
process of finalising its requirements and strategy for suitable ILM solutions.
We are currently evaluating various solutions for data archiving and ILM,”
reveals its Vice-president for IT, Munish Mittal.
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| What is disk-to-disk backup? |
| In a disk-to-disk backup, the data is
written to a disk-based backup box and then on tape. This intermediate step
returns control to the server or storage array so that it can do more productive
things such as serving up files to employees who need them urgently. However,
tape continues to be used for long-term archiving, offsite removable storage
and disaster recovery.
The downside of disk-to-disk
backup?
- Disk-to-disk
backup is not archived storage.
- To have a complete
backup solution, disk-to-disk needs to be combined with a more permanent
storage system such as optical or tape in order to maintain multiple
copies of the data taken at different points of time.
- The reason that
a majority of enterprises don’t use disk-to-disk backup is its
relatively higher cost vis-à-vis tape.
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For a few backups more
There are many solutions to shrink the backup window. Two of the most widely
used methods are disk-to-disk-to-tape and server-free backup. “If the production
environment is not 24x7, we would recommend the first method. However, if the
production environment is 24x7 and mission-critical, both should be used,”
recommends Atul Sood, Regional Director of HDS.
Other than this, to shrink the backup window, backups should be scheduled during
non-peak hours so that normal processing within the server remains unhampered
and processing resources are available for backup activity.
Sule also suggests that data compression techniques be used to shrink the backup
window for server backups.
HDFC Bank has upgraded its backup technology from DLT to
LTO and from Gen I LTO to GEN II. It has implemented streaming where large databases
are backed up across multiple Gen II tape drives to shorten the backup window.
“We also use disk staging using low-cost SATA disks,” informs Mittal.
Using this has helped improve the overall performance and turnaround time for
backing up data from slow LAN-based clients onto disks instead of tape drives,
and helped release the application for production usage as per business requirements.
“HDFC is also introducing pure disk-based backups for large databases,”
reveals Mittal.
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Tape is not on its way out. Both
disk and tape have growth prospects for vendors, and will co-exist
Sanjit Sinha
Senior Manager
Hardware Research
IDC India
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Tapes are removable and have a shelf
life of 30 years, which makes them perfect for archiving
Jim Simon
Director, Marketing Asia Pacific Quantum
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We use disk-to-disk backup for databases
which are quite large in size and if the data therein requires minimal
restoration time
Sagar Sule
President
Cyquator Technologies
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Disk vs tape
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Getting rid of tape is not advisable,
as it remains the cheapest and most viable way of archiving data. Tapes
are ubiquitous and will continue to be so. More companies are now adopting
a mix-and-match approach to their backup strategies
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Tapes and disks are the most popular secondary storage devices. Multiple options
are available when it comes to disk-based backup. If the functions for which
secondary storage is required are critical to the business— say, a data
warehousing application—most companies use fibre channel technology as
opposed to secondary storage required for archiving e-mail data, where SATA
disks are preferred. Sood says, “We see customers keeping a second copy
of data on the disk itself, and the choice of disk technology is based on the
function for which this data is required. They backup their data to disk, and
then copy the same to tape for offsite storage and archival.”
According to Simon, “Disk (as backup) can sometimes be faster than tape,
particularly when retrieving a specific file.” That said, disk is more
expensive. “Tapes are considered the most economical option to store huge
amounts of data,” continues Simon. Also, there have been advances in tape
technology that have made tapes more robust and durable.
As businesses grow, maintaining data recovery and business continuity are
major challenges that their IT departments face.
However, today’s organisations often cannot make do with tape-only solutions
and that’s how disk-based backup technologies have come on the CIO’s
radar.
Nevertheless, getting rid of tape is not advisable as it remains the cheapest
and most viable way of archiving data. Tapes are everywhere and will continue
to be so. As we go ahead, we will see more companies adopting a mix-and-match
approach to their backup strategies based on their needs.
vertika@expresscomputeronline.com
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