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How does a Snapshot of a LUN work?

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Applies to

Data ONTAP

Answer

  • Snapshot is a locally retained read-only point-in-time image of the data
  • When a snapshot of a LUN is taken, snapshot copies the pointers to the corresponding LUN blocks on the disk. There is no data copied or moved.
  • When there is a change in the LUN data, it is written to new blocks on the disk. Snapshot will continue pointing to the blocks with the old data.
  • Snapshot technology is a feature of Data ONTAP. 

3014144__en_US__3014144snapshot.JPG

  • Use snap delta to display the rate of change of data between snapshot copies. When used without any arguments, it displays the rate of change of data between snapshots for all volumes in the system, or all aggregates in the case of snap delta -A.

snap delta [ vol_name] [ snapshot-name ] [ snapshot-name ]

  • If volume is specified, the rate of change of data is displayed for that particular volume

snap reclaimable <volname snapshot-name>  displays the amount of space that would be reclaimed if the mentioned list of snapshots is deleted from the volume
 

Additional Information

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