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Re: [Veritas-bu] NDMP backups from Netapp using Netbackup
2010-07-27 10:42:50
On Tue, Jul 27, 2010 at 9:27 AM, Len Boyle <Len.Boyle AT sas DOT com> wrote:
Good Morning,
My understanding is that the netapp on disk is keeping track of changed blocks, but that backup software that is written the backup to tape understands files. So the backup software is reading the whole file including both the unchanged blocks and the changed blocks and writing them to tape.
The netapp is using the old unix dump command to read the files and write them to tape. Netbackup adds its header files to the backup stream. Other then software such as snap mirror or snap vault I do not believe that the netapp have an api for only passing the changed blocks to the backup software.
One could wonder if this will change with the new world of dedupe.
Just imagine how ugly your restores could get if you only backed up the changed blocks. If you update block 1 on day 1, block 2 on day 2, block 3 on day 3 and then restore, you'd need all 3 incrementals. With file-based incrementals, you only need the last one. If you're backing up to disk, the first option isn't so bad. With backups to tape, this would be horrible.
.../Ed _______________________________________________
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