Online Snapshots
Capture point-in-time images quickly
- Recover quickly at disk speeds to known good state
- Eliminate back-up window
- Provide “live” environment for analysis, development & testing
- Save snapshots in lower tier, thin-provisioned storage without taking up space on premium storage devices
Once you’ve tried online snapshots, you can’t live without them. Snapshots capture a known good point-in-time that may be used for several purposes without scheduling lengthy back-up windows. It may give you a recovery point to undo a patch or file deletion. Or it may be used to feed business intelligence analysis. They are also commonly used to verify new software enhancements in test and development before being put into production.
Snapshots are invaluable in cloning working system images to provision identical new servers. Although snapshots utilities are commonplace in operating systems, hypervisors, backup software, and disk arrays, capturing them at the SAN level affords some major advantages. For one, there is no dependency on host software. Nor does it consume host resources. And you don’t need mutually compatible disk arrays. You can snap the contents of disks on a tier one array and place it on a tier 2 or tier 3 device, rather than tie up expensive space on the top-of-the-line equipment.
In fact, DataCore snapshots reduce capacity consumption in two ways:
- They can be set to capture only changes from the original source and
- They may reside on thinly-provisioned volumes.
DataCore snapshots may be triggered from Windows Virtual Shadow Copy (VSS-compliant) applications that temporarily quiesce the application and flush O.S. caches to ensure a consistent recovery image.
There’s some impressive magic that goes into making DataCore snapshots fast and lean. Part of it comes from the realization that generally, only a few blocks on most devices really experience much change. With that in mind, the snapshot can reference the original unchanged blocks most of the time without taking up any extra room. We need only keep a separate, unmodified copy of those blocks that get updated. And that copy is taken on the first change to that block, effectively giving us the frozen point-in-time. Think of the software as a traffic cop. If the block is unchanged, read from the source. If the block has been changed, read from the copy of the original contents kept in a separate bucket.
DataCore gives you several snapshot variations. We just described the “Differential Snapshot”. You can also ask it to completely clone the source disk in the background. We refer to it as a “Full Clone” You may refresh the snapshot to a later point-in-time using the “Update Snapshot” command, or you can completely replace the source with an earlier snapshot using the “Revert” command. That one is reserved for those cases when you have to undo changes.