snapcenter SQL backups & restores

FelixZhou · ‎2020-04-22

learning SnapCenter with SQL, a few questions you may help. thanks in advance.

1. when we restore SQL database from a snapshot, will all blocks/whole database or only changed blocks be copied back?

2. when we make a snapshot on an individual SQL database, is the snapshot only made on this database or the original volume?

3. can the SQL restore also be run on SQL server or only allow on SnapCenter?

4. what is the difference between database migration and clone? I thought the clone is a way of migration.

5. will a database clone process actually map the snapshot to a new host?

6. can snapshots be allocated to different volumes or always have to stick with original volumes?

7. is the backup verification really a need? seems a different host will be needed.

nboggs · ‎2020-05-22

I apologize for the delay in response I will answer the ones that I can however, I am not an SnapCenter expert.

1. Snapshots actually Just locks old blocks so when restoring from a snapshot the pointers just get moved back to the old blocks and the pointers to the new changed blocks get removed unlocking them.

2. Snapshots are always made in the volume.

3. I am unsure of that one.

4. A clone is just a vserver attached to a snapshot so it doesn't actually take up any extra space. It is only when the close is broken off is a new volume created.

5. see above

6. Snapshots are always in the same volume. I'm not positive on how this works with SnapCenter but i know with snapmirrors and snapvaults you can have a secondary volume that duplicates and or stores extra snapshots from the orginal.

7. I would recommend doing verification as a backup isn't really a good backup until it is tested. Since these are database backups the database and the host have to be "paused" when the snapshot is created to ensure that the snapshot is consistent. Let me know if this answers your questions. I may be able to explain more or it might be time to open a case to get to a snapcenter specialists that can explain better.