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The realities of virtual tape libraries |
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By Hywel Matthews
14 Jan 2009 | SearchStorage.co.UK
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A lot of us had parents that told us we could do virtually anything we wanted. Sometimes they were right and we became pilots, firemen, train drivers or rocket scientists. As for me, I was never able to get that F1 racing job, so IT beckoned.
What our parents didn't foresee all those years ago was a future where we could do virtual things. We all know we can turn a physical bit of kit into multiple servers with a sprinkling of virtualisation magic, which is something my parents will never comprehend. Einstein had it all wrong, it turns out, because it's been proven that you can create something out of nothing.
Sprinkle virtualisation magic over a tape library and what do you get? Something where you can virtually (for the most part; almost; just about; more or less) do anything in the real backup world, but where you can actually (in essence; in fact; in reality) eject a virtual tape that doesn't exist … now please take me to the loony bin.
Why would you want to eject a virtual tape out of a device that doesn't exist? For the same reason people jump out of planes with bed sheets tucked into rucksacks on their backs -- because they can. Where does the tape go? Who knows? Who cares! If you did this to a physical tape in the real world you would see the tape sitting in a CAP/MAP, but as you've ejected a tape that doesn't exist, you've ejected a non-existent tape into a CAP/MAP that also doesn't exist. You'll start to care when you've worked out that the only way to get the ejected tape that doesn't exist back into the non-existent library is via the virtual tape library (VTL) console which, of course, is protected by an administration username and password that you don't know.
Can you send virtual tapes offsite? Err, yes. Well, not in a physical entity, but with replication between VTLs. With more virtualisation magic dust, the tape that doesn't exist can exist in another location.
VTLs are a bit like losing coins in the car: You know they're between the seat and the handbrake, but you can't see them. Why did they fall out? Because they can.
About the author: Hywel Matthews is a senior consultant at GlassHouse Technologies (UK), a global provider of IT infrastructure services. Hywel has more than 12 years of experience in the IT Industry and nine years of experience in backup, recovery, disaster recovery, systems and storage.
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