Tom Goldberg
Forum Replies Created
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Lee,
The Cache-A VTAPE always contains whatever you last put in it unless you erase it upon Ejecting your tape (in tar format). If you did not erase, when you put in a new tape the system will always ask you what you want to do with that data.
Typically, you will always want to “Erase VTAPE” upon ejecting any tape, doing so will prevent any warning like the one you are reporting.
If you do get that warning, but don’t want the leftover data in the VTAPE, just select the “Use TAPE” option.
If you get this warning and discover that you do want that data, then eject and put the data somewhere or use the System Tools > Utilities > Disconnect VTAPE feature.
Once you get past the Cache-A trying to keep you from losing data you may want, CatDV should be able to restore your content to the VTAPE and move a copy back to its source directory.
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Mike,
Because we have looked at this tape, we know that the EOD (End Of Data) maker is at the beginning of the tape. As I explained to you, the only way we know of that this can happen is if the tape is erased.
We are advised by our OEM partners HP, that the standards of the LTO consortium do not allow anyone to read data past the EOD marker. This is why we would have to send the tape to HP as a consortium member for recovery and have offered to do so. That offer still stands.
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Jonathan,
When mounted to a Mac, the partition is invisible, thus there is no attribute that can be seen by the MacOS.
I would note further that even using getfattr under Linux can give you misleading results as LTFS automatically puts copies of anything written to the Index partition also onto the Data partition.
If anyone out there knows of a better way to do this, please post on this thread!
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Just to underscore Kevin’s answer, DLT was a sole-sourced tape technology acquired by Quantum with a capacity of 40GB/tape. Quantum further developed it under the SDLT name (sometimes also referred to as DLT) up 2007 with uncompressed capacities to 400GB. At the time LTO was at generation 4 with 300GB capacity.
Around that time, Quantum dropped development on their proprietary SDLT solutions as it became obvious that LTO was going to be the accepted standard, being supported by 3 manufacturers, Quantum, IBM, and HP. Physically the tapes are very similar but with LTO-6 now at 2.5TB uncompressed capacity and a roadmap to over 12TB/tape, it has become the only man standing for most tape-based archiving applications in our industry.
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Hi Ashley,
If you want to take an easy way out, use a Cache-A appliance – we have built the Discovery requirement into our products with an option to automatically put that metadata.xml file into the index partition.
If you want to check if your implementation was able to do that, here is how you can look at which partition a file is on:
getfattr -n user.ltfs.partition pathname_to_file
Where pathname_to_file is the full pathname of the file in question.Partition “a” is the index partition and “b” is the data partition.
Good luck!
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Very sorry Tim,
I did not mean to misrepresent your product nor start a posting war (nor mistype your trademark).
When I claim that tar can be read on a Mac, while not supported by OSX, there are several ways to do so, including, I believe a solution from you.
Is it not correct to state that BRU is a proprietary format?
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Eric,
We’ve seen many delivery specs for LTO over the years.
Early on, specs from the likes of NBC/Universal and Technicolor have been around for a long time and don’t necessarily make sense for everyone (i.e. requiring a separate tar for each film frame in a clip sequence).
Within the last few months, we’ve seen the Discovery Communications spec that relies on LTFS and is becoming a requirement for all their content suppliers. It makes requirements upon the tape writing software to place their metadata information on the index track which we are accommodating in our next software release.
This latest spec from Spike states that tapes must be written in non-proprietary formats like Bru or Retrospect (which we consider proprietary) but can’t be written in LTFS (which we consider open). Go figure! At least they accept tar, which we’ve always supported.
Bottom line is that interchange on LTO is becoming more and more common and LTFS appears to be a driving factor in many cases, though there is still a large contingent requesting tar for interchange.
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
[Eric Weiner] “I have a Cache-A unit, which can also span tapes, but if you lose one of those tape in a span for what ever reason, you don’t only lose the tape, you lose everything it is spanning too. “
Eric’s comment is really not correct. When you lose or damage a tape in a Cache-A tar spanned set, you may lose the ability to restore individual files or folders, but any remaining data in the set can still be recovered. With a Cache-A LTFS spanned set, as each tape within the set is a proper LTFS volume in and of itself, you really only lose whatever was on the damaged/lost tape.
We always recommend avoiding spanning or at least keeping spanned sets to a minimum number of tapes because that is just better archiving practice and recovery of subsets of your data will always be easier and faster.
It should be noted that Cache-A written tapes in tar and LTFS are both open formats and our tapes can be read on any Mac, PC or Linux system supporting those formats – I believe that today, that is not normally true of Bru or Archiware tapes.
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
Shannon,
When using Cache-A gear, you will absolutely never overwrite any data on a tape unless you erase it.
If you check the Tape Information dialog to ensure that you will have plenty of space for whatever you want to add, you will have no issues in this regard. (We do recommend you leave 5-10% of the capacity of each tape to ensure you don’t end up overfilling.)
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com -
[Bob Zelin] “I can only ASSUME that this means that they don’t want BRU or Cache-A .tar files because they can’t be read on “generic hardware” “
Bob – I want to clearly point out that Cache-A .tar files are readable on generic hardware – we use standard POSIX tar under the hood to write them. The only thing that is not readable without Cache-A hardware is our table of contents file which is just one small file at the end of data.
As John notes every Linux and Unix machine ships with tar, and tar solutions are also available for both PC and Mac environments.
Tom Goldberg
Cache-A Corporation
433 Park Point Drive #285
Golden, CO 80401
mailto:tom.goldberg@cache-a.com
https://cache-a.com