Yes it would make life more interesting. With the new backup support for what was called pure disk the backup data is going to disk and only the changed blocks. But if I understand things the netapp would have to have code installed on it that would understand the pure disk api.
As to writing the changed blocks to tape, I believe that is what is happing with the netbackup/Oracle change block support. I believe that the Oracle support keeps all the information about which change blocks exist and their location in a database. Oracle rman then can fetch the blocks from netbackup. Netbackup then returns the blocks to Oracle from disk or tape. With the tapeid support on the current tape drives this is not as hard as one might think. If one had 100 changed blocks out of 100000 blocks in a file/table the extra work of keeping track of the changed blocks might be a lot less them moving the whole file around. But the complexity of the backup meta data increases. From: Ed Wilts [mailto:ewi...@ewilts.org] Sent: Tuesday, July 27, 2010 10:43 AM To: Len Boyle Cc: VERITAS-BU@MAILMAN.ENG.AUBURN.EDU Subject: Re: [Veritas-bu] NDMP backups from Netapp using Netbackup On Tue, Jul 27, 2010 at 9:27 AM, Len Boyle <len.bo...@sas.com<mailto:len.bo...@sas.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 Ed Wilts, RHCE, BCFP, BCSD, SCSP, SCSE ewi...@ewilts.org<mailto:ewi...@ewilts.org> [http://www.images.wisestamp.com/linkedin.png]Linkedin<http://www.linkedin.com/in/ewilts>
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