‘Dual Target’ CentricStor V4 tackles enterprise storage headaches head-on

Fujitsu Siemens Computers’ (FSC)
CentricStor virtual tape appliance (VTA) V4, announced this week for Q1/08
release, will be the first to introduce ‘dual target’ to allow data back-up to
disk-based cache or tape.

Through this it can become an integrated part of information
lifecycle management (ILM) tiered storage environments.

Marcus Schneider, director of product
marketing with Fujitsu Siemens Computers’ (FSC) storage business, identified four
major challenges in storage at present, which the new CentricStor release will
help address: data growth, longer retention (10, 30+, 100 years), limited (or
no) backup window (e.g. 24/7 working and multiple time zones for major
enterprises), and cost/energy consumption (also highlighted as ‘green’). “These
are issues for eight out of 10 companies,” he said.

Compliance and legislative rules are the main
reason for longer retention. For older and inactive data in this category,
retrieval speed is not a big issue. So the most cost-effective and energy-efficient
approach is to get it onto offline tape since tapes only consume energy when
being accessed, unlike disk. All virtual tape library (VTL) systems such as
CentricStor speed initial backup (onto disk divided into virtual ‘tape’ units),
then transfer the backed-up data onto any number of physical tape drives according
to pre-set automated procedures at a more leisurely pace in the background.

However, dual target takes this a little
further. ILM systems consider the importance of the data and use rules to define
which storage tier to place data on; but VTL hardware/software normally appears
as just the off-line tape storage tier. Yet if it is known there is a high chance
specific data will need retrieval in the near future, and/or that retrieval from
tape will be too slow, then the VTL can retain it on disk.

Effectively, CentricStor now has a
‘near-line’ disk capability, which can hence be considered as part of an overall
ILM regime—perhaps making it an easier decision to offload more unused data from
the main system. However, since most enterprises will already have near-line disk
storage in place, this may, in practice, be primarily a performance issue (and will
expand the CentricStor configuration at the expense of central storage). It may
also assist in meeting stringent data recovery SLAs.

The need to retain more data on disk is the
reason for the scalability of disk cache—now up to 1 petabyte—and there is a
trebling of the number of logical tape volumes to 1,500,000. But CentricStor
VTA V4 also offers thin provisioning to allocate disk storage only as needed,
which makes disk utilisation more efficient, slows near-line capacity growth—and
consequent energy usage increase. Provision for de-duplication (at present from
third party solutions) is also included, to further reduce storage.

Clearly, CentricStor is conceived primarily
as an enterprise VTL solution, but Schneider also saw the possibility of
smaller companies using the disk only option. At the other end of the scale are
large enterprises such as finance companies and banks who hold a ‘mirror’ data
centre some distance away from the main data centre for disaster recovery
purposes. He mentioned two such configurations in Germany at 120km and 300km apart
respectively, that used fibre channel links; clearly, the CentricStor appliance is
part of this—and it includes synchronised disk cache mirroring.

That leaves the limited back-up window
issue. All VTL systems dramatically reduce on-line back-up time by writing to
disk instead of directly to tape. Being stand-alone, CentricStor may increase
performance, while scheduled maintenance downtime can be eliminated through
multiple nodes where one can be taken out without stopping system operation. But it will
only fully achieve zero back-up window as part of a continuous data protection
(CDP) system.

Finally, FSC has expanded its service and
maintenance with quarterly or half-yearly system health checks, which may be carried
out remotely or on-site. So, all in all FSC’s CentricStor now has a good answer
for most enterprises’ concerns about long-term backup; VTA V4 places CentricStor
at the top end of the VTL market.