LTFS writing XML to index partition

[Tom Goldberg]

Jon,

I was also confused as I was getting the same result in my tests – this thread actually contains the answer:

[Jonathan Applebaum] “Important note: The index partition is typically not updated immediately, so don’t run this command until you’re sure that has occurred (though a more frequent interval can be specified, the index is always written when a tape is unmounted).”

So try ejecting, reinserting and then check your xattr’s (thanks Jonathan!)

Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com

[Greg Luce]

For those using linux, the appropriate command is
attr -g ltfs.partition /location/filename.extension

It should say
Attribute "ltfs.partition" had a 1 byte value for /location/filename.extension:
a

[Joe Kaczorowski]

Tom,

I am wondering when this discovery option was built into the cache-A appliance? I have recently been trying to develop workflow for my company to make deliverables to Discovery and trying to figure out what equipment to buy. I rented a Pro Cache LTO deck and found it clunky to use at best. I was very disappointed in the connectivity of the drive to the machine and the graphical user interface of the software.

I am under the impression that Cache-A has some of the best stuff out there and have to believe that what I was using was hopefully just out dated? Would you be able to point me in the direction to find more information on seeing how this workflow actually works? I would love to speak to someone in more detail in regards to our specific workflows and needs and how cache-A could help with that?

Thank you very much for your time,
Joe

[Tom Goldberg]

Joe,

Cache-A added the Discovery Format Rule option as of our version 3.2.4 in May of this year.
Our releases and release notes are always posted on our Support web page at https://www.cache-a.com/support.php and software updates are available for download by request also from our web site.

If you’d like to discuss operations or drive connectivity further, I’d be happy to help you out, please drop me an email at the address below.

Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com

[Vincent Lavares]

Thank you all for this information. I found this to be such a tremendous help in writing out these tapes! One question though. If I am verifying that the metadata.xml file lives on partition “a” by doing the following:

attr -g ltfs.partition /mnt/tape/ltfs0/metadata.xml
and the return message is “a”

Do I then delete the file from /mnt/tape/ltfs0 after this “validation” in order to comply with Discovery’s tech specs? Because if I don’t, it appears that the xml file resides on the same partition (b) as the data.

[Tom Goldberg]

Hi Vincent,

If you are using the Cache-A Discovery format, the metadata.xml file will be on the index partition and you really don’t need to check.

If you insist on double checking, be sure to eject the tape and reinsert after the last write to ensure that the information about where that file is written has been updated.

We recommend never deleting anything from a tape – in fact data will still be wherever it was, just no longer visible through LTFS.

Tom Goldberg
TGCS
30201 Rainbow Hill Rd.
Evergreen, CO 80439
mailto:tomgoldberg@gmail.com
https://tomgoldberg.net

[Greg Luce]

Hi Vincent,

If you’re using the standard Linux binaries you also should not delete metadata.xml
The linux ltfs mount command lists the index partition with everything else, so you don’t have to worry about metadata.xml showing up in ls or what have you. As long as your attr -g ltfs.partition command shows what you want it to, you should be good to go!

[Vincent Lavares]

Thanks Tom! But what if I’m not using Cache-A? If I’m listing the volumes in linux, the metadata.xml file appears to reside on the same partition as the MAIN and AUDIO data. I looked over the Cache-A LTFS file layout and that apears to normal. I’m just questioning it against the spec sheet I was given.

[Vincent Lavares]

Thanks for the info Greg!