2010-07-08 06:17 AM
My understanding of snapshots is that the initial snapshot contains all pointers to all of the data block and that subsequent snapshots only contain pointers to new and changed blocks (deleted blocks are unreferenced and removed when the snapshot is deleted). If you were to move an SMVI snapshot outside of a NetApp (say with NDMP to a Data Domain), does it reconstitute the snapshot with all of the data blocks (static, new, changed and minus the deleted)?
2010-07-08 07:09 AM
Each snapshot contains pointers to every block in the filesystem (a single block can be referenced by many snapshots). Thus, the snapshots are independent of each other. If you were to do a full dump of a snapshot it would contain the entire filesystem as it was at that point in time.
2010-07-08 11:13 AM
Have you considered NetApp data protection solutions for this? I think you may have been on the right track in thinking about only new and changed blocks... our replication engines will only transfer new and changed blocks. Basically we compare snapshots and replicate the delta. This is true for our mirroring solution and our D2D backup & recovery solution. The advantage is that you only have to do a single full transfer. Every transfer (mirror or backup) afterwards is done via changed blocks only. This saves on storage requirements, backup times, and costs. It also gives you the opportunity to increase your recovery point objectives. Deduplication can also be enabled with these solutions for futher savings.
Using SnapVault (for D2D backup & recovery), you can maintain your current SMVI retention on NetApp primary storage and then maintain longer term vaulting retention on a NetApp destination. If you'd like more information on this please let me know!