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How can I know how much free space in a tape?
- Thread starter kiros
- Start date
julianbarnett
Technical User
Not that I know of. Some utilities such as Legato and Netbackup attempt to estimate this based on expected capacity. If you are compressing the data this makes it even harder to guage since compressibility varies from file to file.
All you do know is how much data (in terms of bytes on disk) you have written, and the capacity of the tape. You can write some sort of count into your backups that estimates the free space remaining using these figures. As a start estimate that if you are using a compressed tape you are getting 2:1 compression - you will need to adjust your figures based upon experience.
P.S. compressed data on disk (gzip, .Z etc.) will not compress further when copied to tape.
JB
All you do know is how much data (in terms of bytes on disk) you have written, and the capacity of the tape. You can write some sort of count into your backups that estimates the free space remaining using these figures. As a start estimate that if you are using a compressed tape you are getting 2:1 compression - you will need to adjust your figures based upon experience.
P.S. compressed data on disk (gzip, .Z etc.) will not compress further when copied to tape.
JB
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