Tape Compression

[reinstalled]

Is it accurate to say that a backup job to tape at /dev/rmt/0n
will default to use compression if the HW supports it?
Or do I have to specify the c switch?

This is a Solaris 9 system.

Thanks,

 

[cndcadams]

reinstalled;

As long as you have the correct device drivers for the tape unit then solaris will by default use the highest compression available.


Thanks

CA

 

[reinstalled]

Thanks CA,

Thats what I thought.

 

[daFranze]

/dev/rmt/0n - the non compressing, non rewinding tape device
/dev/rmt/0cn - the highest available compressing, non rewinding tape device

Best Regards, Franz
--
UNIX System Manager from Munich, Germany

 

[reinstalled]

Thanks Franz.

When I use the 0cn device name I get a the following message in my log and the backup doesn't run.

Device /dev/rmt/0cn: This tape device requires the CAPACITY option.

How do I use the Capacity option?

Much Thanks,

 

[tuka]

If you run this command:

ls -Ll /dev/rmt/1* (you can use any of the instances)

The Major and Minor numbers are displayed. All instances which share the same minor numbers will have the same properties.

33,3165 (33 is the major number and 3165 is the minor number)

 

[daFranze]

>> Device /dev/rmt/0cn: This tape device requires the CAPACITY option.

just doubleckecked this message on sunsolve: 0 hits!
Where do you get this message (syslog, console, terminal)? Who throws this message (OS, Application)?

Best Regards, Franz
--
UNIX System Manager from Munich, Germany

 

[reinstalled]

Ignore that CAPCITY message. When we redirected the backup job to use the device /0cn instead of 0n we changed the physical name but not the logical in Sybase. It just got confused.

The job ran fine the last two nights when specifying
to use compression with the 0cn device name. This is troubling to me as ioctl should use the highest available correct?

 

[KenCunningham]

I don't quite understand what you are asking - 0cn is the highest available compressed non-rewind device.

I don't mind people who aren't what they seem. I just wish they'd make their mind up.

 

[daFranze]

I agree with Ken: I do not understand the question/problem.
And yes: ./0cn is the device with the highest data compression rate available (HW will write in compressing mode)

Best Regards, Franz
--
UNIX System Manager from Munich, Germany