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Re-using TAPES

Re-using TAPES

hi everybody,

I wanted to know the life of the DDS IV tape cartridges. i.e age wise and write wise.
Also for the DLT IV tape cartridges.



Re: Re-using TAPES

I have done some research on this last year. The tape life ( archive storage ) for a DLT IV and DDS tape is upto 30 years. The durability ( Average head passes ) for a DLT IV is 1,000,000 and for a DDS tape is 2000. The white paper http://www.quantum.com/src/whitepapers/wp_tapedurability.htm
helps in understanding the life and durability of a DLT IV media.
Patrick Wessel
Honored Contributor

Re: Re-using TAPES

take a look in the FAQs of the DDS Manufacturers Group
There is no good troubleshooting with bad data
Darrel Louis
Honored Contributor

Re: Re-using TAPES


Check on the following url:

Things to consider:
- Good place to save tapes
- Connect DLT to Dedicated SCSI bus, good for keeping tape in streaming mode, best for tape life cycle.

Have fun
Carlos Fernandez Riera
Honored Contributor

Re: Re-using TAPES

About DDS tapes:

There is 4 types of DDS ( 1-2-3-4). DDS 1&2 dont must be used after 50-60 re-writing.

DDS3 cartriges have a new coating and the degradation is fewer. In DDS3 users guide say 100 insertion to write.

About DDS4 i am not experienced.



Dave Wherry
Esteemed Contributor

Re: Re-using TAPES

About the last reply. I have seen DDS 2 tapes used over 200 times and still working fine.
I had a remote site where an enginerd was supposed to change the tapes for me daily. fbackup writes a counter on the tape and will not use it once it has hit 100. To deal with this remotely I simply used tar to write a small file to the tape which overwrote the fbackup header info. fbackup then looked at it as a new tape.
The tape still wasn't changed for me and it hit 100 uses again. The joys of remote support.
Rotate your tapes and watch for errors. Also clean the drives, just not too often as that is hard on the heads.
Tim Malnati
Honored Contributor

Re: Re-using TAPES

A while back during a data center move we had the opportunity to attempt to load in some really old tapes. What we found is that most tapes more than 10 years old were typically unreadable on most equipment. Some of them we were able to get the data from on a real sensitive tape drive, but there were a lot that this drive would not decipher either. Tapes more than 5 years old start getting questionable. It continues to bring up an interesting tought though... I can't begin to imagine how many old 9 tracks are out there in some vault that can't even be read.

The 30 year thing on DLT's is theorecical. I'm sure that they are more reliable, but DLT technology is still less than 10 years old, so it's a good guess in my mind, far from proven. If you are really looking for long term storage, CD-R is the direction I would look toward. Plastic does not destablize the same way that tape does.
Carlos Fernandez Riera
Honored Contributor

Re: Re-using TAPES


I am reading ( rereading) a HP handbook titled 'Success with DDS Media' ( P/N C1500-90911 - 1993). This book says :

"storage Life :

Test show that data can succesfully be stored on DDS cartiges for a period of 30 years. You should give each cartrige a full pass in the drive at least once a year to prevent sticking. Store the cartrige according to the envi....."

Also, all user guides say you must avoid transferring data when temperature is changing by more than 10 degrees per hour.

Cartriges recorded 10 years ago must be in DAT or DDS1 format, and at that drives writes in 512bytes blocks; now 1024bytes, so it is 'difficult' for new drives to read oldest cartriges.


Number of insertions to write will be higher if amount of data is few. DDS drives realocate blocks on tape. So if your backups are sort ( < 1Gb) , the drive could invalidate lots of blocks.

The source attached on previous link will tell how many write after read error have been needed in each backup session, number of loads of tape, and estimated capacity available on tape.

News DDS-2 tapes (4/8gb) estimates about 3900000K. When this values is near to 3000000 the tape is degradated and must be discarded.

Best regards.
Dave Wherry
Esteemed Contributor

Re: Re-using TAPES

I agree with what you've found in the handbook. Those are good guidelines. My backup was over 1GB and I would not recommend using a tape 200+ times. That is too risky. I guess I just had a good drive and a good tape.
If you have a drive failure and it is replaced by HP, they will bring out a refurbished drive. They do not send out new drives for replacement, especially for an older format like DDS. Although the drive may work fine you will likely have more errors with the replacement drive. Just aging technology.
I like to be more conservative than the guidelines. DAT tapes are cheap enough to use 10 or 12 times and then rotate out to long term storage such as monthly or yearly backups. With DLT tape around $70 it's a little harder to cost justify rotating the tapes out. But, if you start with a new tape format you still have to do your long term tapes. The tape may have only been used a couple of times. A lot of variables to consider.
For the purposes of the question here, I would stick pretty close to the guidelines you found. Better safe than sorry.