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| tape drive 1 | ---- | switch 1 | ---- hba1 | backup server | hba2 ---- | switch 2 | -----| tape drive 2 |

Our backup server has 2 FC HBAs. Each is zoned into a different drive on the back of the tape library via a separate switch.

Each tape is connected to a different switch presumably to allow for the switch to fail yet allow the backup server to still have one accessible tape.

We seem to have lost an HBA. As a temporary measure, is it possible to move the tape drive into the other switch which is still connected to the backup server and zone the one HBA into both FC Tape drives?

---- | switch 1 | ---- hba1 | backup server | hba2 ---- | switch 2 | -----| tape drive 2 | + | tape drive 1 |

Will this confuse Backup Exec seeing both tape drives coming from one HBA, or dos EMC's HBAnywere software or drivers abstract this away knowledge away from the application and just present the tape drives to the Operating System regardless of which HBA they are appearing..?

My suspicion would be that you can have as many LUNS as you want (within OS Max) coming from one HBA or the other HBA and probably Backup Exec wouldn't know the difference, but I can't risk just changing these things without the concrete knowledge that I'm not going to make things worse. I don't want to risk Backup Exec's access to the last working tape drive.

Thanks!

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1 Answer 1

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Yes you can do that, like you say just rezone it and no backupexec won't give a hoot about it - the LUN will remain the same as it's still the same tape drive going through the same HBA - there's no part of the path that cares about the switching infrastructure and neither will HBAnywhere. Basically your understanding is spot-on :)

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Amazing Chopper! I was just sending a comment your way after reading your answer to a similar question, all the while you were answering my question! Haha! –  Kenny Feb 23 '12 at 11:48
    
Many thanks! Where do you learn how to design storage networks? @Chopper3 - I have a CS degree but everything I've learned about SAN has been on-the-job research projects driven by the need for maintaining existing kit, so know only very little, but find the LAN and SAN design fascinating. –  Kenny Feb 23 '12 at 11:50
    
Oh Chopper3: If I repatch it'll be coming on on a different HBA - It appears in Backup Exec the tape drive has properties "Port 4" Lun 0, which matches HBAnywhere's "OS Device Name": \\.\Scsi4 - and the working drive has "Port 3" in backup exec, and "OS Device Name: \\.\Scsi3" in HBAnywhere. Once again scared if I repatch the drive into the other switch (and therefore into the other HBA on the sever) I won't be able to go back to a working config.. –  Kenny Feb 23 '12 at 12:12
    
Thanks for the kind comments - where to learn? I'm just old and have been exposed to lots and lots of different problems/kit/people over the years - you really can't shortcut experience. Best thing to do is work for massive companies with lots of spare kit for you to break and fix. As for your query I must have mis-read, thought you were going to connect the first HBA to the second switch - that'd work a treat, not certain how BE will deal with just moving the tape, worst comes to worst it's a bus rescan and/or a bit of reconfig - personally I'd link hba1 to switch 2 if that makes sense. –  Chopper3 Feb 23 '12 at 13:02
    
Unfortunately it's hba1 that seems to have died. I've tried changing switch port, replacing the SFP on the switch, and replacing the fibre "patch lead" so seems to be the hba itself not working. Unless changing which PCI slots the HBAs are in will bring this back, I'll just have to try moving the switch the tape's patched into.. many thanks. –  Kenny Feb 23 '12 at 14:38

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