In the storage world, snapshots are a point-in-time copy of data. They have been around for some time and are increasingly being used by IT to protect stored data. A snapshot copies the metadata (nee index) of the data instead of copying the data itself. This means taking a snapshot is almost always instantaneous. This is one of the primary advantages of storage-based snapshots—they eliminate backup windows. In traditional backup deployments, applications either have to be taken off-line or suffer from degraded performance during backups (which is why traditional backups typically happen during off-peak hours). This means snapshot-based backups can be taken more frequently, improving recovery point objectives.
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