[Rear-users] Calculating tar speed on tapes

Schlomo Schapiro schlomo at schapiro.org
Mon Sep 27 13:06:02 CEST 2010


Hi,

could you maybe post your solution to the list for discussion? Maybe
this is in general a good idea to post patches to the list for
discussion, for example func works that way.

If your tar solution counts the data after the gzip, why could it not
also be used for the tar-to-file version?

Again, what you found there is the result of "I need some info and don't
have much time" so that any improvement will be appreciated.

Maybe you can run a simple NETFS-to-NFS test to make sure that your code
works there as well?

Kind Regards,
Schlomo

Am 27.09.2010 11:43, schrieb Dag Wieers:
> Hi,
> 
> Currently the 50_make_backup.sh script calculates the 'backup' progress by 
> measuring the destination file size over time. This however does not work 
> on tape-devices, in fact, on tape-devices it is very hard to know exactly 
> how much has been transferred, and lacking any knowledge of how much is 
> going to be backed up, we are mostly in the dark.
> 
> Even after the backup has finished it is unclear how much data has been 
> stored on tape, only tar itself knows. Because of this I rewrote the 
> calculation logic to make tar log this information (--totals) and then use 
> that information to display it after the backup.
> 
> For the progress information for normal (non-tape) tar backups, I left the 
> logic in place.
> 
> Would such a patch be acceptable ?
> 
> PS It's by doing this that I noticed the original script had a typo 
> showing incorrect transfer-speeds.
> 




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