Drive Serial Numbers Match...Sorta
I am configuring a new VTL with NetBackup 7.1 on Windows. When I create new tape drives on the virtual library, for reasons I can’t even begin to imagine, the algorithm used to generate serial numbers for each drive creates matching serial numbers with the exception of the last character. For example, I have one drive that has the serial number 1234565789A and another drive with the serial number 123456789a. There are some drives that have a period or a dash for the last character. Windows isn't case sensitive so I'm thinking this is going to be an issue for NetBackup. The vendor won't even consider discussing the issue unless I can prove it's going to be a problem. I have to crash my backups before they will help me.
I have never seen any other library behave like this, virtual or physical. I asked the same question at the Symantec Customer Forum last month and they all laughed, as did I, wondering why, with the millions of possible combinations, why would any algorithm be written that would duplicate drive serial numbers? And I’m not talking about 1 or 2 drives. Of the 360 drives I have created so far, I have 74 pairs with upper/lower case and 6 other drives with characters other than alpha/numeric in the serial number.
Has anyone experienced this with tape drive serial numbers? If I can get an article or technical document that would really be helpful in pushing this back to the vendor. When I run a tpautoconf -report_disc, I get many drives as "Missing". I deleted the drives from the GUI, rescanned the media servers, and the drives returned to normal. By that evening, I had jobs failing unable to find any available tape drives. We are experiencing other issues with the VTL so the vendor doesn't think the serial numbers are the problem. The way they dismissed me, I'd love to prove otherwise.
Thanks in advance for any help anyone can provide.
Randy
p.s. Here's a screenshot of some of the serial numbers...
Comments
"We are experiencing other
"We are experiencing other issues with the VTL so the vendor doesn't think the serial numbers are the problem."
So do they offer solution other than serial number correction?
good Will backing-up
Can i ask why you are
Can i ask why you are configuring so many drives?
NetBackup can multiplex up to 32 so each drive can do 32 jobs and being a VTL there is no lag with doing it as it is disk really.
360 drives can do 11,520 jobs at a time - do you need that many?
Parhaps with less drives you wouldnt habe the issue?
360 - 74 - 6 = 280
Shame - i was expecting the answer to be 256 !
Authorised Symantec Consultant
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NetBackup doesn't generate
NetBackup doesn't generate serial numbers ...
It is up to the VTL to 'make' itself' look like a 'real' library, including generating the drive serial numbers.
NBU has absolutely no knowledge of a 'VTL', it just thinks it is a 'real' library.
Martin (Symantec TSE)
The reason the drives are
The reason the drives are showing as missing, is that the drive with serial number xxx has 'disappeared', or is still visible, but the serial number has changed.
Sorry, but this is nothing to do with NBU.
Martin
Just a thought and not sure
Just a thought and not sure if i have read your error note correctly but ....
If when you first set up some drives and brought them into NetBackup it would have created the Storage Unit and this would have been set to the number of drives that existed.
If you then added more drives, re-scanned the new drives would have been added but the Storage Unit would not have been updated as it already exisited
So if your first test had 100 drives and now you have 360 then the Storage Unit Would still be set to 100.
Hope this and my earlier comments help
Authorised Symantec Consultant
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To find out why devices are
To find out why devices are disappearing, add VERBOSE entry to ...\volmgr\vm.conf on all media servers connecting to the VTL and restart NBU. Device level errors will be logged in Event Viewer System and Application logs.
Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows.
Handy NBU links
Drive Serial Numbers Match...Sorta
First, thank you all for the responses, that's why I love this place.
Second, let me clarify a little more. For now, the VTL continues to experience hardware issues. But when the device is working properly, sometimes for 2 days in a row, NetBackup works great so maybe I'm worried about nothing. Let's put this in terms of a physical tape library because that's all NBU sees anyway.
Let's say I bought a tape library with 50 drives. Some of the drives in the library arrived with matching serial numbers EXCEPT for one of the characters in DRIVE1 is upper case and on DRIVE2, the exact same serial number with the same character in lower case. Because my servers are Windows and Windows is not case sensitive, I'm worried that NBU is going to see the two drives as the same drive. I haven't seen that behavior yet but until I can get the vendor to stabilize the hardware, I don't spend a lot of time troubleshooting NBU even though I'm getting failed jobs almost everyday.
Does that paint a better picture? I'm just worried about the "duplicate" serial numbers causing problems later. I don't think I've stayed on line long enough to really test NBU with the new VTL to determine if those serial numbers are going to be a problem.
OK - got you now, although i
OK - got you now, although i had the feeling earlier in the thread that you were experiensing issues with "available tape drives" hence my comment about checking the number of drives actually in the storage unit.
When buying "Real" tape drives the serial number issue would not happen as they are always unique - a bit like a MAC address.
So it may well cause you an issue in view of the Upper / Lower case serial numbers and again could i suggest that perhaps you use less drives and and more multiplexing as it may well be that once you go past a certain number (256 i suggested in my earlier thread - although that did not seem to quite add up) this serial number problem is appearing.
Exactly which make and model of VTL is this? I know that the Quantum ones do have limit on the number of tape drives which are much lower that your figures (max of 55 for some models)
I know this vaires between vendors but most seem to suggest a large performance hit if using a lot of drives anyway.
Authorised Symantec Consultant
Don't forget to give a "Thumbs Up" or mark as "Solution" if someones advice has helped you.
NBU is case sensitive -
NBU IS case sensitive - remember that the product is ported from Unix!
As per previous post, add VERBOSE entry to vm.conf and check Event Viewer logs for the reason for disappearing drives.
Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows.
Handy NBU links
Thank you Ms. van den Berg,
Thank you Ms. van den Berg, you're a peach!! That's Texas for you're Da Bomb...which is Philedelphia for you're allright in my book.
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