Surestore DAT40 - Backup incomplete

[Tim Knight]

We have a HP SureStore DAT40
Tape backup.

I have a few questions that hopefully somebody out there can answer.

1. How many backups or the expected Shelf life do the tapes have?
This may help with question 2

2. Our backup system runs to approx 94-96% then ejects the tape/s. We have tried running a cleaning tape through, changed to other tapes, etc. The only thing we haven't tried is a brand new tape.

We have 6 tapes presently 1 for each day of the working week + 1 spare.

we puchased and started using them 12 march 2003
so maximum 12 backups per tape. They are auto formatted each time before backup

Any help would be much appreciated!

[Eugeny Brychkov]

Tim,
look at this page http://www.hp.com/products1/storage/products/storagemedia/tape_dds/faqs.html
I suspect that drive is ejecting tape because tape got full. Remember: you can backup only approximately 20GB of compressed data (thus with drive hardware compression ratio 1:1). Anyway the first action I would do is to look into backup utility event/error log
Eugeny

[Eugeny Brychkov]

And BTW, do not forget to clean drive regularly: after every 5 full backups or 20 tape pulling hours (in your schedule it should be done on weekend). Throw away expired cleaning tapes
Eugeny

[BR732038]

http://h20015.www2.hp.com/en/document.jhtml?lc=en&docName=lpg50333

100 full backups and a 10 year shelf life if you observe the environmental and storage criteria:

http://h20015.www2.hp.com/en/document.jhtml?lc=en&docName=lpg50113


Are you saying that your tapes are ejected before the backup is completed or that you only get 94-96% capacity on the tapes .... ?

[Tim Knight]

Firstly Eugeny,

You where right about the tape being full. I put in another tape and it started from 94% and completed.
Which brings me to more questions.

Now that we need to backup over 20 gig should We:

A. compress the data to get 40 gig on the tape?

B. purchase 40 gig tapes if available?

C. Just use two tapes per backup session?

And secondly to Madoc
Sorry I didn't explain myself very well.
The backup session stoped or stalled at 94% - 96%
and ejected the tape
I didn't know what to do so I cancelled the backup session, same thing everyday for the last 5 days.

Thanks all for you input so far

[Eugeny Brychkov]

A. compress the data to get 40 gig on the tape?
Native DAT40 capacity is 20GB. Native means with no compression. Thus if you'll turn off software and hardware compression you'll be able to store only 20GB. If you'll turn on hardware OR softare compression (zipping files consider as software compression) then with compression ratio 2:1 you'll be able to store 40GB, with compression ratio 4:1 - 80GB, 10:1 - 200 GB etc :o) The only value remains - native capacity is 20GB. Remember not to turn on BOTH hardware and software compression. It will cause data overhead. Note: if file(s) are already compressed (with winzip, gzip etc) then turn off hardware compression;

B. purchase 40 gig tapes if available?
See (A). Native tape's capacity is 20GB, there're no 40GB tapes for DAT40;

C. Just use two tapes per backup session?
If finally you'll not be able to fit all your data into one tape then use second, third etc

Good luck!
Eugeny

[Rothery Harris]

You could move up to DAT72 which is 36GB native. Its also backwards compatible with your existing DDS-4.
Sometimes if the error rate increase the capacity of a DAT drive will fall because of data is being re-written following a read after write failure.

[BR732038]

more info on compression:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xc30e36e69499d611abdb0090277a778c,00.html