Forever cycling through device discovery - Cannot open exchanger control device ([122] The data area passed to a system call is too small. )

I spent some time with the HPE response centre on this problem -- an IBM 3584 tape library that Data Protector could discover (badly) but couldn't use and kept cycling back through path discovery.

[Normal] From: MSM@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:49:07 AM
Media session 2016/01/15-23 started.

[Normal] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:49:07 AM
STARTING Media Agent "IBM 3584 L32"

[Warning] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:59:10 AM
[90:59]   Changer0:0:0:1
Cannot open exchanger control device (Details unknown.)

[Warning] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:59:10 AM
The device "IBM 3584 L32" could not be opened("Device could not be accessed") 

[Normal] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:59:10 AM
Starting the device path discovery process. 

[Normal] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:59:12 AM
A new path(s) "Changer0:0:0:1" found for device "IBM 3584 L32" and stored. 

[Normal] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 11:59:12 AM
Device path discovery process finished. 

[Critical] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 12:09:15 PM
[90:59]   dp.ifost.org.au : Changer0:0:0:1
Cannot open exchanger control device ([122] The data area passed to a system call is too small. )

[Normal] From: UMA@dp.ifost.org.au "IBM 3584 L32"  Time: 15/01/2016 12:09:15 PM
ABORTED Media Agent "IBM 3584 L32"


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                      0 cartridges out of 0 successfully scanned.
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In the end, it was a Data Protector bug (in Data Protector 9.05, and probably earlier versions too). It's fixed with QCIM2A65833_IB2, available to anyone with a support contract. (Speaking of support contracts, I offer a Support Contract Review with a money-saved or money-back guarantee).

Greg Baker is an independent consultant who happens to do a lot of work on HPE DataProtector. He is the author of the only published books on HP Data Protector (http://www.ifost.org.au/books/#dp). He works with HPE and HPE partner companies to solve the hardest big-data problems (especially around backup). See more at IFOST's DataProtector pages at http://www.ifost.org.au/dataprotector, or visit the online store for Data Protector products, licenses and renewals at http://store.data-protector.net/