large file spans tapes

[eliu]

Hi,

 

 

 

I'm writing a single 200GB file to tape and Retrospect is doing a great job of switching tapes automatically when it runs out of space. One thing that has me concerned though, is the fact that after it switches to a new tape there is a long period of lots of network activity (between the retrospect server and the server holding the file) and zero tape activity. After several hours it starts writing to tape and everything progresses normally until there is another tape switch.

 

 

 

Does anybody know what is going on here? Is it comparing its records to the original file to find where it left off? I've noticed that this doesn't seem to happen when there backup source contains many different files. I'm concerned because it seems to be adding a great deal of time to the backup procedure. If I could turn this off somehow I could probably get it done in half the time, which means I could do all the backups in off hours.

 

 

 

Thanks,

 

bye.

[AmyJ]

When Retrospect spans media, it has to do a byte by byte file compare on the file that was spanned across media to ensure that it is being copied properly. Typically this won't take a noticible amount of time. However, a 200g single file is bound to be very time consuming. You may want to exclude this file from your backup, or use a third party utility to segment the file into more manageable chunks of data.