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LTO-5 Tape question: 1.5 TB Native / 3.0 TB Compressed

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Aaron Duprey
LTO-5 Tape question: 1.5 TB Native / 3.0 TB Compressed
on Jan 15, 2015 at 7:05:55 pm

I've been backing up projects using LTO-5 / Cache-A, and in general, it's been working great. I'm a little confused about the tape capacities, though. We use SONY Ultrium 5 tapes, and I get 1.5TB per tape. However, the tapes tout a capacity of 1.5 Native / 3.0TB 'compressed'.

How would I go about archiving my projects such that I'd get 3.0TB per tape? How does this compression happen? Is there a setting that I'm missing somewhere? I've tried formatting tapes in both Cache-A and LTFS formats, but the capacity stays at 1.5TB.

Thanks in advance.


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David Roth Weiss
Re: LTO-5 Tape question: 1.5 TB Native / 3.0 TB Compressed
on Jan 15, 2015 at 7:40:18 pm

You can't recompress video, it's ALL compressed right out of the camera, so you should not set your LTO to compress video at all.

FYI, LTO compression is for document files such...

David Roth Weiss
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David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.


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Aaron Duprey
Re: LTO-5 Tape question: 1.5 TB Native / 3.0 TB Compressed
on Jan 15, 2015 at 7:44:21 pm

I guess that's what I thought. Thanks.

I've got a project that's 1.7 TB that I was hoping to keep to one tape, but I'll just span it across two.


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Tim Jones
Re: LTO-5 Tape question: 1.5 TB Native / 3.0 TB Compressed
on Jan 15, 2015 at 9:41:11 pm

We've been trying to get the vendors to stop promoting the compressed capacity for tapes for years. Even a highly mail or document-centric environment won't see 2:1 (2.6:1 claimed on LTO-6). We've tested 100's of environments from Windows desktops to Unix storage servers and the average that we see is closer to 1.6:1.

For media storage, they all need to drop the compressed values since the drives can't compress this type of data any further. You'll always see 1:1 (or a slight level of compression if your data contains PDFs or other business-side documents). You're best bet is to assume 1:1 and then be excited if you get more than that onto a tape.

Fortunately, the compression algorithms used in the drives are smart and recognize when they can't compress the incoming data stream.

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


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