Data tape backup used to be the preserve of IT and database admins, seeking to manage a so called ‘tier3’ backup and offsite repository for their material. In those days data tape systems were expensive, complicated, and generally uncommon outside of large corporates and government organisations.
Fast forward to the modern world of file based large format cameras, and the reality for the most part is, that in this ’tapeless’ world, more and more material ends up on er…tape.
However, thankfully in this scenario, tape archives are now faster, simpler and friendlier, and also provide one of the most cost effective methods to store valuable ‘digital file negative’ to a medium that can be moved onto a shelf, with a longevity of at least several decades (according to their manufacturers that is).
The development of the LTO (Linear Tape Open) Ulthrium format us underpinned by a trio of manufacturers consisting of HP, IBM and Quantum, ostensibly with the purpose of reducing industry ‘fragmentation’ around tape formats and thus potentially affecting the buying decisions of companies looking for an ‘open’ long term archiving solution. Lets face it, in this type of environment, the last thing we really need are a bunch of competing tape formats and standards. There are however still competitive developments from the likes of IBM, Sony and Oracle to add to the mix and keep the incentive to innovate and compete in play.
However in this particular area of IT, format longevity and compatibility is of paramount importance. Crucially, part of the LTO design specification requires that a ‘current’ generation LTO format drive write to the current, and one prior generation of cartridge, and ‘read’ back from two. Thus for example, LTO-7 drives will write to LTO-7 and LTO-6 cartridges, and read from LTO-7, LTO-6 and LTO-5 cassettes. An LTO-5 drive however, cannot read nor write from or to a higher generation device such as LTO-6. As you would expect, based on historical progress of the format, capacity has roughly doubled ‘per generation’. LTO-7 drives store 6TB of uncompressed, and about 15TB of compressed content. Read speeds are roughly around double that of LTO-6, again with the speed averaging around 315 MB/sec. It can be confusing when vendors talk about tape specifications, as their inclination is to refer to their compressed capacity and compressed data rate numbers as these at a glance are far more flattering.
As our source material is mostly video and audio data, compression is typically not a consideration as most of the time, very little benefit would be derived from deploying it. Thus don’t be confused if you see LTO-7 numbers of 15TB and 750MB/sec. This is the compression talking and it can be very misleading.
One of the solid aspects of the LTO consortium has been their stewardship of a tape format which has successfully scaled in capacity and speed in reasonable line with their development roadmap. This gives licensees, manufacturers and users confidence in the ability of the technology to provide a stable route to compatibility, migration and interoperability. The ambition doesn’t stop at LTO-8 either as we can see from the infograph below:
Source:Storage CH Blog
It is no wonder then that the LTO Ulthrium format has been the mainstay of products shipped by Xendata, one of our favourite archiving product manufacturers. The larger capacity of the LTO-7 format gives us the ability to manage much larger archives at a pretty similar cost to previous generations.
Xendata’s line of compete system LTO-7 archives sees the entry level occupied by the SXL-8 series with 42TB of archive capacity via a 8 bay autoloader. It includes what Xendata describe as ‘unlimited offline capacity’ which means you write out a tape set, export it from the library, pop them on the shelf, and then load it up and begin the process again. The system remembers the tapes based on their barcode, and will request you reload them in the event of a restore being required.
From the entry level system, capacity extends right up to the SXL-6500 featuring a 180TB of LTO-7 capacity extendable to 1.6 Petabytes and supporting up to 10 LTO-7 devices.
Xendata archives feature a couple of unique capabilities. First, a notion of a cache disk drive that can be shared and written to over the network, and secondly once the file has been written away from the cache to tape, the material is deleted, leaving behind a tiny ’stub’ file. A user seeking to restore material either via drag and drop, or from the cache via a 3rd party piece of software will effectively trigger a restore the moment the file stub is requested to be copied to a different destination. These two features allows rich set of workflow options.
Finally media costs for LTO-7 cartridges are around £130 pounds per cartridge at time of writing and provide a very cost effective backup strategy indeed.