BRU PE says tape is full…when it shouldn’t be!

[Tim Jones]

There are a couple of things that can affect how much data is written onto a tape –

Tape condition / drive condition – This can cause soft errors – where data blocks must be written to the tape multiple times to make sure that the blocks are written properly – and Hard errors – where the tape reports a lower available capacity than you would expect because of errors on the tape that cause segments of the media to be unusable.

Software overhead – the software used will have overhead associated with how the data is written to the tape – the software’s format. In much the same way as a file written to a disk filesystem will cause eventual capacity loss because there will be a “smallest writeable size” (sometimes referred to as a cluster), most backup software has similar “smallest writeable size. For BRU, that overhead is around 18%. This is not wasted space, but rather the extra data that we track for your files to insure the most reliable recovery of your data.

If you combine these situations, you could witness a rather noticeable drop in storage capacity as it relates to your filesystem data.

What were you seeing previously with your LTO-4 drive and BRU PE?

Tim
—
Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters!

[Jason Kalinoski]

Thanks Tim.

I need to get this figured out so we decided it was a good time to upgrade to 3.0 and get some pro tech support involved…I’ll follow up with your support guys.

Jason

[Diane Akam]

Hi, I upgraded my BRU-PE to 3.0 and have found that the “how many tapes” estimation is quite off. I use LTO-4’s (800gig native) and found even with just a 250 gig project program is estimating 2 LTO tapes. So I loaded up my archive with 640gigs – it obviously said to use 2 tapes, and left it to run overnight. In the morning it was all done – just on one tape. I was glad it worked, but now frustrated that the estimation is so off. So now I’m just allowing the 18% free space and archiving up to 650gigs for each tape.

Diane Akam
dnafilms.ca

[Tim Jones]

Hi Diane,

Have you opened a ticket with our support team to find out what’s going on (support.bru.com)? I don’t want to turn the Cow into TOLIS Group Support :).

Tim
—
Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters!

[Su-jeng Sang]

What happened with this at the end? Did you solve it??

[Jason Kalinoski]

Yes, the problem was that the record heads on the LTO deck were going bad.

Apparently if there’s write errors, the data gets re-written but the bad blocks are still on the tape (or something like that)

We replaced the heads and all worked well. BRU support diagnosed the problem.