compatable DLT autoloaders or not?

[CA804561]

We have a new HP SStore Tape Autoloader (made 01/02)Model 1/9 and a HP DLT autoloader Model-418 (made03/1999). Using software compression only with Backup Exec V8.60.3878.
Testing seems to indicate the old Model 418 produces tapes that can be restored using the new model but a backup in the new MODEL 1/9 isn't read in the Model 418. Get "bad tape" error. Initially I was able to interchange DLT tapes between them..I thought.
AT the moment I do not seem able to do two backups using either device onto the same tape and restore from either device. Is this a factof life or do I have a hardware problem. Hp's Tape Utility says both are health...
I am also getting large numbers of soft errors a new tape had 268 within

[CA628575 · Accepted solution]

From the description you provide it appears that your old unit uses a DLT4000 drive while the new unit uses a DLT8000 drive. This would explain your symptoms. DLT8000 drives will be able to read cartridges written by a DLT4000 drive, but not vice versa. The DLT8000 is a newer drive that uses a higher data density when writing data which is not understood the DLT4000 drive.

There is a mode where a DLT8000 drive can be forced to write at DLT4000 density, which would make tapes written on it backward compatible with your DLT4000 drive. But this is non-default behaviour and will be dependent on your software and hardware configuration.

[BR19682]

Hi there.
Jan's idea sounds reasonable.
Another thing : why using software compression ? these drives have hardware compression available. Backups shopuld be shorter and the CPU load much less.
Rgds
Alexander M. Ermes

[CA713937]

> Another thing : why using software compression ? these drives have hardware compression available. Backups shopuld be shorter and the CPU load much less.

I agree - hardware compression is usually quicker, uses much less CPU time, and may help the drive stream better. However, software compression may provide a better compression rate. The compression algorithm in the DLT drives uses a form of Limpel Ziv compression, that is best suited for text data and repeated byte patterns. Software compression can pick the best algorithm for each specific file, while often does better than the "one size fits all" algorithm used in hardware.