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Let's talk tape storage and technology

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Tim Jones
Let's talk tape storage and technology
on Jul 10, 2012 at 3:36:32 am

Hi folks,

As many of you know me from the REDUser forums and other media forums, I've been asked to come online by a few friends on the left coast to add some chatter to the Creative Cow world.

I've been working with tape on all platforms - from embedded oil refinery pigs to the biggest IBM main frames - since 1984 and was involved with the design and engineering of the tape drives manufactured by Archive Corp through the middle '90s. From the earliest Pertec Reel to Reel and QIC24 drives to the latest LTO technologies, I've worked with them all.

While here, I'm happy to answer general tape technology and archival workflow questions as well as general questions about our (TOLIS Group) BRU products, but I don't want to turn my presence here into sales event or an alternative to our tech support team.

If you've been wondering about LTO technology, SAS or Fibre Channel storage options, or if those AIT-2 or DDS-3 DAT tapes are still any good, ask away and I'll do my best to answer.

Tim
--
Tim Jones
CTO - TOLIS Group, Inc.
http://www.productionbackup.com
BRU ... because it's the RESTORE that matters!


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Andrew Richards
Re: Let's talk tape storage and technology
on Jul 11, 2012 at 1:41:16 am

Glad to have you here, this isn't a terribly active forum on the COW, but having a knowledgeable voice to fill us in on tape goings-on is always a good thing.

I have an LTO question: the spec calls for backward read-compatibility for two prior generations. Do any of the drive OEMs exceed that? Like, could we see an LTO-6 drive that can read LTO-3?

Best,
Andy


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Tim Jones
Re: Let's talk tape storage and technology
on Jul 11, 2012 at 3:10:57 am

With LTO, it's pretty clear cut and the biggest issue is the track width and density on the tapes. After a while, the track width to head width ratio becomes so large that the result is that the later model head is reading noise rather than data.

Imagine if you're driving down a one lane road - pretty easy to keep your vehicle in the track. Expand that to a two lane road with no lines and you can still pretty much stay to one side or the other. Now, expand that the 10 lanes wide with what appear to be random lane markers. It would be very tough to stay in a "lane". However, if your vehicle were ten times wider, you're back to the original parameters - easy to stay in your lane and the random lines are just something to roll over.

There was a discussion of a custom assembly that would offer two sets of heads and more reel speeds, but the cost became so prohibitive that it is more cost effective to purchase two different devices. As a matter of point, you can still purchase an LTO-2 pCSCI and SAS drive today.

Taking it a step further, if you use BRU as your high level tape format, you can even copy the data directly from one technology to another meaning that you could readily migrate your LTO-3 tapes to LTO-8 (in 2020) without a need to re-archive the data. This is one of the ways that we protect against technology obsolescence. You could even migrate from tape to those little colored chips form the original Star Trek when they become available :-).

Tim
--
Tim Jones
CTO - TOLIS Group, Inc.
http://www.productionbackup.com
BRU ... because it's the RESTORE that matters!


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Tim Jones
Re: Let's talk tape storage and technology
on Jul 11, 2012 at 3:40:02 pm

With LTO, it's pretty clear cut and the biggest issue is the track width and density on the tapes. After a while, the track width to head width ratio becomes so large that the result is that the later model head is reading noise rather than data.

Imagine if you're driving down a one lane road - pretty easy to keep your vehicle in the track. Expand that to a two lane road with no lines and you can still pretty much stay to one side or the other. Now, expand that the 10 lanes wide with what appear to be random lane markers. It would be very tough to stay in a "lane". However, if your vehicle were ten times wider, you're back to the original parameters - easy to stay in your lane and the random lines are just something to roll over.

There was a discussion of a custom assembly that would offer two sets of heads and more reel speeds, but the cost became so prohibitive that it is more cost effective to purchase two different devices. As a matter of point, you can still purchase an LTO-2 pCSCI and SAS drive today.

Taking it a step further, if you use BRU as your high level tape format, you can even copy the data directly from one technology to another meaning that you could readily migrate your LTO-3 tapes to LTO-8 (in 2020) without a need to re-archive the data. This is one of the ways that we protect against technology obsolescence. You could even migrate from tape to those little colored chips form the original Star Trek when they become available :-).

Tim
--
Tim Jones
CTO - TOLIS Group, Inc.
http://www.productionbackup.com
BRU ... because it's the RESTORE that matters!


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