This article aims to clear durability and availability misconceptions associated with cloud storage solutions like Enterprise NAS Storage. When the organization bestows storage-related responsibilities like backup, DR and archiving on a third-party cloud vendor, it needs to consider availability and durability both.
Here is why there can’t be a trade-off between durability and availability.
Durability
Durability in terms of hardware is its ability to endure damage. While there can be many sources of damage for example, environmental factors like humidity, temperature, wear and tear. Natural disasters in disaster-prone areas can cause irreversible damage. Nonetheless, the damage is inevitable, let’s take a look at hard drive failure.
Hard drive failure
Regardless of the cause of failure, hard drive failure generally accounts for high percentage reasons of data loss. Datacenters without temperature regulators and high humidity can increase the chances of hard drive failure in NAS Data Storage appliances. To avoid hardware failure, the equipment must be durable and acquired from known vendors.
Since data retention and archiving solutions have to be there for the long term. There is more guarantee on the durable hard drives.
Erasure coding
NAS Storage solutions come with erasure coding to minimize the effect of any error or erasures. The data is divided in chunks, replicated and stored in different hard drives. If a few hard drives in NAS architecture fail, the data can be reconstructed using reconstruction codes and replicas. Reed-Solomon erasure coding is one way this can be achieved.
Factoring in everything from physical and environmental damage tolerance along with error-correction ability accounts for the durability of the NAS storage appliances.
Availability: Ups and Downs
Coming to availability, though durability somewhat assures availability but this can also have another aspect to it. Availability accounts for the total amount of time that the data can be access. Let’s say per year. If the promised availability by the cloud vendor is three nines i.e. 99.9% then the downtime would be 8.77 hours per year.
This is mentioned in the SLAs of private cloud vendors and needs to be addressed if the organization cannot afford this downtime.
Conclusion
To conclude, durability and availability are both hardware related don’t let software cloud storage gateway your judgment. High availability can be achieved with durable hardware. Hardware failure is inevitable; we can only minimize the chances of failure. Furthermore, redundancy provided by NAS storage appliances makes lives easier.
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