storage ICT
Coupled with the fact that tapes can be stored offline without consuming power or valuable datacenter space, tape is clearly a more viable long-term storage platform than disk. Data protected on disk-only is further vulnerable to the network environment in a way that tape isn’t, simply because disk is online
option for Assisted Self-Maintenance - end-users can readily replace components when issues arise under instruction from technical support. Rather than waiting hours or days for on-site engineers to arrive, IT admins can perform routine maintenance themselves.
In light of the concerns around long-term capacity requirements, tape provides the perfect balance between cost, capacity and scalability. Unlike disk, which requires a large investment once its fixed capacity is fully utilised, tape libraries can scale in a very modular way as requirements increase. Tape can be added in small quantities, increasing over time by small increments without requiring a significant overhaul or disruption. Capacity on Demand features in mid-range libraries permit slot increases of as little as five at a time - perfect for organisations whose IT budgets require more of a slow and steady approach to expenditure over more erratic but larger-scale investments. Furthermore, a single library can be used to manage many tapes, even beyond the library’s slot count. Tapes can be added beyond the full slot count by taking tapes out of the library when it is full, and adding new tapes as needed, and by re-using existing tapes when the data is no longer needed. Truly modular tape libraries should also allow drives to be added as needed, increasing throughput should an organisation suddenly experience a significant spike in the amount of information needing to be backed up.
. While typical disk life varies based on usage patterns its reliable life compared to tape is short. Modern tape technologies can typically store data for 30 years or more. Coupled with the fact that tapes can be stored offline without consuming power or valuable datacenter space, tape is clearly a more viable long-term storage platform than disk. Data protected on disk-only is further vulnerable to the network environment in a way that tape isn’t, simply because disk is online.
The most recent leap-forward in terms of tape reliability and one which has silenced many tape nay-sayers is the ability to verify the health of data residing on tapes. While data integrity has been addressed through multiple mechanisms for disk, organisations until recently have been unable to address the data integrity
For mid-range organisations there is also the issue of reliability. One analyst from Data Mobility Group suggests that organisations should start to consider disk refreshes after the three year mark2
issues that occur after the data is written to tape media. Only recently has the capability for customers to address the integrity of data on tape become a reality. Data Integrity Verification allows end-user organisations to check the health of tapes before they are used, perform a quick scan of data immediately after it is written to tape, and even check an entire tape to ensure it can be read. End-users can then set triggers to check the health of tapes over time - ensuring data is retrievable.
While these reliability and manageability features may all be important considerations for mid-size organisations, the importance of financial considerations must not be underestimated, particularly in the current economic climate. In terms of straight up acquisition costs per GB tape comes in significantly cheaper than disk- around 75% cheaper (or even higher in some cases) for comparable capacity. But this disparity becomes even more staggering when you begin to consider the longer-term cost of ownership. Again, numbers vary based on each individual use-cases, but the Clipper Group puts the TCO of disk over a twelve year period somewhere around 15 times higher than tape. This is based not only on the higher cost per GB of disk, but also the increased density and lower power and cooling costs associated with tape. While improvements in technology - deduplication, thin-provisioning etc. - are helping customers to lower the TCO of their disk infrastructures, there is still a significant gap between the short-and long-term cost of disk and tape.
Regardless of the size of an organization, data handling and storage has emerged as one of the key business strategies and imperatives over the coming years. While these challenges may not necessarily be new to larger organisations, mid-size organisations are having to deal with new storage requirements and new demands from end-users which have the potential to test already stretched IT budgets and resources. Finding the right balance between cost, performance, reliability and ease of management is key when making decisions about the kind of infrastructure required to support the growth in data.
Given its traditional strengths around cost and density, coupled with recent improvements in reliability and automation its almost certainly time to think about the role tape can play in meeting long-term data storage needs.
1. Moore, Fred. “Tape Technology Leaps Forward in the Third Era,” White Paper for Oracle, June 2010. 2. Brandel, Mary. “Vendors; Hard Drive Failure Rates: Myth or Metric?
http://www.computerworld.com/s/article/9073158/Vendor_disk_ failure_rates_Myth_or_metric
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www.dcsuk.info I February 2012
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