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HP LTO-6 tape won't eject - sloppy qc in manufacturing; BRU PE bandwidth for 2 LTO-6 drives

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Sam Lee
HP LTO-6 tape won't eject - sloppy qc in manufacturing; BRU PE bandwidth for 2 LTO-6 drives
on Jun 5, 2017 at 1:55:34 pm

I average about 200 LTO-6 new tapes per month of high volume data archival. But for the past year or so, I'm seeing two of the HP Enterprise purple LTO-6 tapes won't eject the drive. It got stuck 3/4 of the way. Had to turn off the power when it eject out in order to pull out the tape. What bad is over the weekend I'm not able to restore the 2nd half of the data. It simply would stuck there at the same place for half a day. The drive simply cease to move. This is on BRU. Fortunately the restoration process restored all of the critical project files and I was able to re-render the animation. But I wouldn't bet my luck on other assets for this.

When I changed to another tape, no problem. It would eject fine. I recalled when I archive this particular tape everything was OK. But the tape going bad is another concern. Storage condition wise it's in normal 65-75 degree room. Tapes are placed inside dust proof containers.

Is there any way I can repair the LTO-6 tape mechanism to get the data back? The obvious thing is to archive to two tape volumes. LTO-6 media are pretty cheap now - about $28/tape. This may be the case.

When I archive to 2 LTO-6 drives, BRU PE is my first choice. I'm curious if the bandwidth is divided. For example. I have a 3 Tb hdds directly connected to a Mac Pro via a USB3/e-SATA ext drive dock. I'm getting about 150-160 MB/s of sustained data transfer on a single HP LTO-6 drive. But if I put two drives, will the data transfer be split in half for the 2 drives? If this is the case, there is really no real benefit of having 2 drives since the time it take will be roughly the same. Only downside to this method is having to do the archive process twice.


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Tim Jones
Re: HP LTO-6 tape won't eject - sloppy qc in manufacturing; BRU PE bandwidth for 2 LTO-6 drives
on Jun 6, 2017 at 6:15:40 am

Hi Sam,

If you're witnessing physical tape hangs like that, it's a very good idea to run HPE's L&TT diagnostics on the drive to find out what the drive mechanism thinks happened.

In the case of BRU PE and dual jobs/doubler, you will need to be able to see the average throughput in the read side of your storage device. We recommend Black Magic Disk Speed Test as a good sample tool. There is also a way to run BRU's engine from the command line and get an unadulterated number from your source drive:

Create a folder with 60-70GB of media data on the source drive (more is fine, but will just take longer).
Open a Terminal and run the following command substituting the path of your prepared folder for the place holder:
bru -cvvvf /dev/null -b 2m /Volumes/PlaceHolder/Folder | tail -1

The process will run with no output until it finishes. At the end of the run, you'll see a line that looks like this:
bru: [I181] wrote 36295680 blocks (72591360 KBytes) on volume [1], 0:02:02, 595011 KB/sec

In my case, I could easily run 3 drives with enough overhead to keep them spinning. The rule of thumb is 1.2 times the rated native throughput, so each LTO-6 would consume ~190MB/sec to stream.

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


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Sam Lee
Re: HP LTO-6 tape won't eject - sloppy qc in manufacturing; BRU PE bandwidth for 2 LTO-6 drives
on Jun 7, 2017 at 2:50:36 pm

Thanks for the tips. I'll look into the terminal commands.

I'm curious to know if BRU is capable of performing sequential tape volume archives with two LTO-# drives? Let's say I have two HP LTO-6 drives and I don't use the doubler mode. I don't always need to do 2 set for certain type of data. I simply alternative between tapes when doing multi tape archive. This saves a bit of time when I have to put in the 2nd and beyond tape. Is this possible at all OR it must be a true tape library hardware & firmware?


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