Back-ups are typically performed during off hours with few
personnel available, so
back-up software often emphasises the use of automation. This
typically includes keeping track of back-up schedules, managing the
timely transfer of data volumes to target
tape or
disc locations, handling
compression and
data deduplication to reduce media use and
speed the back-up process, and can even include
encryption to secure back-up data against
loss or theft. Some back-up software emphasises "business
intelligence," supporting back-up reporting and analysis to help
IT departments optimise their back-up operations. Alerting
features generate pages and e-mails to keep IT personnel
informed of back-up status, and can even call for assistance if
problems arise.
Lan-free and server-free back-ups
Traditional back-ups stage data onto a server and then push the
data out to a tape drive,
tape library, virtual tape library, or other
storage target. But this is an inefficient approach because the
back-up server is only utilised during the back-up process, and
tremendous network bandwidth is needed to transfer back-up data
to the target, so the Lan is almost unusable during the back-up.
This approach is changing by systematically moving back-ups off
the Lan and onto the San, so you should understand the
difference between Lan-free and server-free back-ups.
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Lan-free back-ups avoid utilising the user network by employing the
San directly. Data is taken directly from a San disc, handled
through an application server on the San and then passed directly
to another San storage device. The
Fibre Channel San infrastructure allows for
high back-up speeds up to 100MBps. Only metadata about the
back-up data will pass across the Lan, so the impact on Lan
bandwidth is minimal. Server-free back-ups also avoid Lan use,
but further streamline the Lan-free process by reducing the
back-up work performed by the application server -- ideally
moving data directly between San locations. While the resulting
back-up throughput still tops out at about 100 MBps, it uses the
Extended Copy command set (a set of SCSI commands not yet
approved by the American National Standards Institute T10
committee) to minimise the CPU, Ram and I/O overhead on the
application server.
Performance monitoring and reporting
Monitoring is an important part of the back-up process -- it
helps administrators understand how efficiently the back-ups are
being executed in their particular environment. By quantifying the
elements of back-up performance, improvements can be implemented to
optimise or streamline the process. As one example, performance
monitoring might reveal better back-up throughput between 2:00 a.m.
and 5:00 a.m. due to lowest network utilisation. This in turn might
justify a shift in the back-up window. Similarly, low-throughput
from the back-up server to the tape library may explain why excess
"shoe shining" is inflating back-up windows and reducing tape life.
Performance results can highlight the need for network
infrastructure upgrades or media changes.
Back-up software should also provide comprehensive and
configurable reporting features. High-level reports help management
to follow overall back-up statistics on a weekly or monthly basis,
while low-level reporting can identify possible back-up bottlenecks
or media with frequent problems. Alerting is another vital feature
of back-up software, allowing notable events or status updates to
be forwarded to corresponding IT staff. For example, an alert can
indicate that a back-up process failed to run properly, and
immediate attention is required. Monitoring and reporting is
sometimes implemented as standalone products that are separate from
back-up software. Back-up Advisor from EMC is one such standalone
product.
back-up testing
The IT perspective on back-up is changing. Rather than performing
back-ups simply for the sake of copying data, storage
administrators are increasingly addressing back-ups from the
standpoint of recoverability -- backed up data is useless unless it
can actually be recovered. This makes back-up verification and
testing features more important, and any back-up software should
include features that simplify back-up testing.
Beyond verification, organisations must practice their recovery
on a regular basis. In many cases, organisations perform recovery
drills by deleting unneeded "test" files that are maintained on the
server, and then using the back-up software to recover those
files.
General purchase considerations
Back-up software must be selected for its feature set and
suitability for your own particular environment. However, there are
some common issues to consider:
Ease-of-use. Tools that are cumbersome or overly
complicated will not be used to their best potential. An IT staff
should have the opportunity to test several prospective tools in a
lab environment, providing comment on the feature set and user
interface. Advanced features may require a modicum of training but
should demand little, if any, formal training for basic
features.
Compatibility. It's important for software to support the
current -- and possible future -- hardware in your environment.
Homogeneous environments may not be such an issue, but
heterogeneous environments with a variety of hardware may prove
more problematic. Network Data Management Protocol (NDMP) offers an
open protocol that supports back-up tasks in heterogeneous network
environments.
Specialised features. Back-up software will typically
transfer files to tape or disc storage. However, an increasing
number of software tools support data protection features like
archival back-ups (e.g.,
content-addressed storage),
continuous data protection,
snapshots, mirroring or replication. Select
back-up software that complements your back-up emphasis. For
example, a tool like EMC's RecoverPoint allows for frequent
snapshots to disc, while Symantec's Netback-up offers general
purpose tape/disc back-up and restoration.
Application integration. If your goal is to support
specific enterprise applications, consider the level of integration
that the back-up software provides for those applications. For
example, EMC NetWorker software supports modules integrated with
vendor-specific application programming interfaces eliminating
custom script development for applications like IBM Lotus
Notes/Domino, Microsoft Exchange or Sybase.