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Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

Joshua Goi
Frequent Advisor

Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

If not, how can I make it so?

Thanks!
10 REPLIES
RAC_1
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

DDS1 tape can be written in DDS2 drive.
You can not read a tape written in DDS2 drive in DDS1 drive.

That said, if you write a DDS1 tape in DDS2 drive in DDS1 format, you can read in DDS1 and DDS2 drives.

How do you prepare a DDS1 special file??

man mksf

mksf -d tape -H "hardware_address" -b DDS1 /dev/rmt/DDS1

lssf /dev/rmt/DDS1 -- > to check it.

Now for writing a tape on DDS@ drive with DDS1 format use this device

tar -cvf /dev/rmt/DDS1 /tmp/your_file

Anil
There is no substitute to HARDWORK
Rick Garland
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

The solution I remember,

Think downward compatibility. DDS4 will write/read DDS3, DDS3 write/read DDS2, etc...

Joshua Goi
Frequent Advisor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

Hi RAC,

Thanks for your answer. What happens when you use DDS1 tape using default device file /dev/rmt/0mn using a DDS2 Tape drive? Can DDS1 Tape drive read this?
Sanjay_6
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

I don't think so.

Hope this helps.

Regds
RAC_1
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

lssf /dev/rmt/0mn
(DDS2 tape drive) This is best density DDS2 drive speical file. So you cant read this tape in DDS1 drive.

Anil
There is no substitute to HARDWORK
Patrick Wallek
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

If you use write to a 90m tape (DDS1) in a DDS2 drive, then YES you SHOULD be able to read that 90m tape in a DDS1 drive.
john kingsley
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

An easy way to create the DDS1 compatable device file is to use SAM:

SAM --> Peripheral Devices --> Tape Drives
Select the device
Actions --> Create Device Files --> Create Custom Device File...
Select [Density] --> DDS1

This will create a file /dev/rmt/c#t#d#DDS1C
Paul Mai
Advisor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

Hi RAC,

shouldn't the best density device file contain the string "BEST" in the filename?
Bill Hassell
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?

There are only two choices for modern tape drive densitites: normal and compressed. It is a misnomer to call this a density. It is simply a data treament prior to reaching the heads--the tape is still recorded the same way. Now DDS-1 is *WAY* back in terms of DDS technology. The very first DDS-1 was commonly called a DAT (but it's not a Digital Audio Tape drive). The problem was that original DDS-1 tapes were 60 meters, the same as DATs, and it was a mess with DAT tapes used in DDS drives. DATs can have a very high error rate (dropouts, etc) and the music is unaffected but for DDS, the error rate is unuseable.

DDS-1 was enhanced with the 90 meter tape but compression was not available. Later, there were DDS-1 DC (Data Compression)drives that used both 60 and 90 meter tapes. At the same time, a media recognition system was developed using holes in the leader. This was mandatory because new DDS standards used thinner tapes that easily wrapped around the tape path in older drives. MRS tape drives will reject (pop out) incompatible tapes (ie, DDS-3 tape into a DDS-2 drive). However, early DDS1 and DAT tapes had no MRS holes so DDS2 (and higher) would treat such tapes as READ-ONLY, the reason is that the error rate is too high to be used in a data application.

So after all that, the most important key is that an official DDS-1 tape be used (90 meters) and do NOT use the *BEST* density since the target tape drive may not understand compressed tapes. DDS-1 is not a very reliable format and with all the special rules (MRS, DAT vs DDS, 60 vs. 90 meters, compressed/uncompresed) so you would be much better off looking for a DDS2 drive to replace your aging DDS1 drive.


Bill Hassell, sysadmin
Marino Meloni_1
Honored Contributor

Re: Can a DDS1 tape written in a DDS2 tape drive readable in a DDS1 tape drive?