DLT starting and stopping all the time

[fv751941]

Hi all,

I use networker 6.1.1 on HP-UX 10.20 with a DLT 7000

When networker takes the backup, the DLT tape starts and stops all the time during writing.

Some people tell me this starting and stopping is not good and causes excessive tape and tape head wear, other people tell me this is normal and it's impossible to feed the DLT fast enough to write continuously.

Can somebody tell me more on this topic ?

Thanks in advance

 

[gerudman]

Hi

With a DLT tape drive you've got to stream the data to get a good backup speed. What happens when it doesn't get data the tape stops and rewinds. Thus when a new backup or saveset backs up it has to go back to the last place written. This wastes a lot time and causes slow backup speed. This stop/start operation will wear out the drive quicker.

In your case it stops while a saveset is busy backing up? I haven't seen this before but would suggest checking all your media settings and if correct, contact you tape drive vendor to inspect the physical drive.

Hope this helps...

George

 

[fv751941]

Thanks for the quick response,

indeed my tape drive starts and stops all the time during the save set. 2 seconds writing, 1 second waiting, 2 seconds writing, 1 second waiting and so on.

What kind of hardware do you have to keep the device streaming ?
I have a HP9000/785-B2000 workstation and the blocksize of the DLT is set to 128 Kb

 

[gerudman]

I'm not sure what our blocksizes are set to (I'll find out from the operators) , but think it's on the default (NT and UNIX differs)

What you can do is to play around with the parallelism.
This configures the amount of savesets that can backup at once. Might decrease you total backup time as well.

cheers
George

 

[Till]

Hi All !

Does anybody know how to backup the DOS-Partition of a
NetWare 5.1 machine ? It runs Client Ver. 4.20.
I know that there is a tool called mountdos.exe, but as far as I know it runs only with NetWare 4.1 machines.

Thanks in advance !