Archive Status and Cache-A

[Bryson Jones]

No ideas on the tape ID thing, let’s see what the Cache-A guys have to say.

The official word on the copied vs archived is this. “Copied means it’s copied it to the vtape. Archived means that additionally it has received confirmation (by reading the transfer log file) that the file has successfully been written to tape. You won’t always get the latter, for example if you archive files by copying them to the vtape, then immediately close the CatDV catalog before it’s written to tape.”

This is from Squarebox and should explain a lot. Tape moves slowly, the confirmation takes a while and since the unit writes through the client app, the catalog can’t close before the whole operation is done.

The archive, however is most likely fine since it made it to the vtape.

bryson

bryson “at” northshoreautomation.com

northshoreautomation.com

[Rolf Howarth]

The Cache-A device is supposed to automatically write files to tape once they’ve been copied to vtape, so to archive a file CatDV copies it to the vtape. If you quit CatDV immediately then the archive status will be “Coped to tape XYZ’ (where CatDV gets the current tape identifier from the Cache-A device), but if you leave it running long enough for CatDV to get confirmation from the Cache-A transfer log then it updates the status to say “Archived to tape XYZ”.

It says “currently on vtape” if the file exists in the vtape folder (ie. the hard disk cache that Cache-A uses). The file normally stays on the Cache-A hard disk until you load a new tape into the drive.

[Tom Goldberg]

Hi Whitney,

I’m not sure why these files weren’t going to tape as you sent them, but that is the root cause of your issue. You had apparently pushed more than 3 TB of data to our VTAPE but the Cache-A did not start actually archiving until you reinserted the tape, whereupon we did what we normally do with more data than what would fit on a tape – tape spanning. When tapes are spanned, they all form a single logical volume and thus are named with the naming convention you noted (i.e. first_tape_name, first_tape_name_2 and so on).

Unfortunately, CatDV does not at this time accommodate spanned sets, so although apparently all your data is safely on tape, CatDV doesn’t know which volume it landed on.

You can either keep this 3 tape spanned set as it is and use the Cache-A’s search function to restore content when you need it or, if you want CatDV to remain in charge, re-archive your stuff to individual tapes.

The CatDV Archive interface nicely reports how much space you’ve used on each tape as you go – in your case, it must have constantly been reporting 0% which should have been a good clue that something wasn’t quite right! If you start archiving to a new tape, note whether those items are actually getting written to tape – you can also easily tell from the Cache-A user interface by noting the Transfer Summary. If it still doesn’t seem to be happening properly, let us know and we’ll look into what might be causing your problem. Don’t forget that your Cache-A share is probably close to full from that last spanned set so you’ll need to be erasing data to make room for new archiving.

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

[Whitney Sickels]

Ok – now I understand the difference! Thanks!

So I need to select the clips, ‘Archive Media Files’ and then leave CatDV open so it can then copy to LTO. Is there a specific setting we need to let it know to “automatically” transfer to LTO or once it’s on vtape it knows to copy over? Should I re-open the catalog to see if the status has changed from Copied to Archived or is there a better way of knowing once it’s on LTO? (Check the Cache-A Tape Directory?)

What should the workflow be like? Do I archive files (daily) as I create them, check the LTO periodically and once it’s full, delete the contents of the vtape, and then put in a new LTO? Or do I have to wait until I have 1.5 TB worth of footage on the vtape and then put a new LTO in?

[Whitney Sickels]

Hi Tom,

Thank you for your response – very helpful.

We would prefer not to span the tapes and re-archive to individual tapes. What is the best way of doing this? Is there a way to tell it not to span or do I need to clear the vtape and essentially re-archive everything via CatDV?

Also, what is this archive interface in CatDV that lets me know how much space is on each tape that you speak of? 🙂 I see the information on Cache-A in Tape Information/Summary, but not in CatDV.

Cheers!
Whitney

[Tom Goldberg]

Hi Whitney,

The best way to avoid spanning is to not put too much on a tape. You can turn it off under System Tools page > Settings tab > Multiple Volumes off. However, if you overfill a tape in this case, you end up with a tape that has no TOC – not good either.

In the CatDV “Archive Media Files” dialog there is a line that displays the Current Tape and in parentheses after the Media ID of the tape is a percentage displayed (45.6% used). To be safe, I would tend to move on to another tape once you get above 90%.

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

[Whitney Sickels]

Ah yes! Thanks for the help and advice, much appreciated.

[Whitney Sickels]

Hi again,

I deleted the VTAPE and am re-archiving everything to avoid tape spanning. However, I just checked some and they say “Archived to (NEW TAPE NAME)”. Sounds good. But when I “Check archive status” it says it’s on the old (spanned) tape number. How do I get it to reference the new tape number?

I checked the LTO and as of now it has about 800 MB lost space… and growing as I continue archiving. What is causing this? It’s Cache-A format (tar).

2.1.16 Cache-A
9.0.6 CatDV

Cheers!

[Rolf Howarth]

Check Archive Status uses the Cache-A API to query the tape a given file is stored on. Unfortunately I believe the API only returns the first tape, whereas it would be more useful if it returned all the tapes, or the last tape.

[Whitney Sickels]

OK, thanks. That’s a shame.

On another note, I just checked the ones I (re)archived yesterday and there seems to be an issue. On some of them, on the Archive details they say ‘Copied to’ (as opposed to ‘Archived to’), even though they all said Archived before I left work yesterday (and I left CatDV open to make sure it had time to copy to LTO). However, I checked the LTO and the file seems to be there. I was told Copied means they are on vtape and Archived means they are on LTO. So why do some still say copied when they are on the LTO? I checked a few files that are marked as copied and they are also on LTO.

After the ‘Archived/Copied to’ there is a semi-colon and something that either has said “currently on vtape” or “currently offline”. What is this referencing? If the former, then it’s still on vtape and the latter it is no longer on vtape?

Cheers.