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What is an Air Gap and Why Does It Matter?

what is an airgap

What is an Air Gap and why does it matter?

Experts forecast that cybercrime is the biggest threat to businesses today and that total costs of attacks will skyrocket to $6 trillion by 2021.  Companies are looking to new solutions to address this risk.  The concept of an air gap was originally developed as a strategy to protect top secret government networks; however, with the onset of cybercrime, the technology is moving to the mainstream.

The basic concept of an air gap is simple – if data cannot be accessed, then it cannot be infected or corrupted. In IT, this is typically implemented as a duplicate copy of production data on a secondary storage system that is offline and thus not connected to any production or public networks.  In practice, this extra data copy is protected from attack and corruption as long as the air gap is maintained.

Companies typically rely on air gap data as a copy of last resort.  That is, the air gap typically augments existing backup, recovery and disaster recovery strategies and provides an added layer of protection.  As an added benefit, it may also enable rapid recovery in the case of a massive attack. However, many vendors use this offering as a strategy to force customers to purchase twice as much hardware (one for production and a matching one for the air gap) which can be costly.  This high cost has limited the adoption of traditional hardware-centric air gap strategies.

There is an additional challenge with an air gap strategy.  The benefit of the air gap solution is that the data is offline, but when offline, data cannot be updated to reflect ongoing changes and so it risks becoming stale.  (Imagine that a remote copy was created a year ago and you lost your data today. How helpful would data from 365 days ago be?) To address the stale data issue, most air gap solutions include a concept of a “temporary” network connection.  The idea is that the air gap solution will be brought online periodically to incorporate the latest changes and then taken back offline. The exact process of how this happens and the frequency of it varies based on the solution and the business requirements.

Some of the common approaches to air gap solutions include:


Array-based air gap

In this traditional, highly capital intensive model, you purchase two disk arrays and configure replication between them.  Replication is scheduled to run at certain times and a network connection between the two systems is opened only during those windows.  During the rest of the time, the second array is offline. Typically you would want to pair this with snapshots to provide the ability to roll back.  The benefit of this approach is fast recoveries; however, the cost is typically extreme as you would need two production quality disk arrays.


Backup-based air gap

In this alternate approach you backup data and then replicate it between a primary and secondary backup appliance.  Like the array-based offering, the replication pipe is opened and closed based on predefined schedules. The downside of this strategy is that it is still expensive and recovery times from the air gapped copy can be lengthy.


Object storage-based air gap

With this strategy, you rely on object storage replication to create the air gap.  Like the others, the network connection between object storage may be opened and closed periodically to create the gap.  However, many on-premises object storage systems and cloud offerings like Amazon Glacier include a WORM option which can enforce retention and prevent data deletion/corruption, and this may be sufficient to remove the need to open and close the network pipe.  The benefit of this approach is the low cost and massive scalability of object storage; however, the challenge is that using traditional technology, recoveries from object storage can be lengthy.

In summary, an air gap is an important protection concept that will only become more critical over time.  There are multiple ways to deliver an air gap, and the object storage approach may be considered the most feasible for companies of all sizes.  The limitations can be meaningful; however, solutions like Actifio’s that natively support object object storage while also delivering instant access can mitigate traditional object weaknesses.  Regardless of the solution you choose, now is the time to think carefully about how an air gap would fit in your infrastructure.

Learn more:  Interested in secure data protection in the cloud?

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