Backup Appliances and Flash (Solid State) Storage

Why Unitrends now uses tiered flash (solid state) storage in our backup appliances

Unitrends recently announced and has begun shipping its third-generation of physical backup appliances. One of the headlines is our use of tiered flash, or solid state, tiered storage in affordable backup appliances. So why did Unitrends choose to use tiered flash (solid state) storage in our backup appliances?

Performance. Scalability. Reliability.

Let’s go through each of these to understand the way that tiered flash storage for our backup appliances help our customers.


This one is simple, right? Flash storage is faster than enterprise rotational storage, so using tiered flash storage increases your performance. Like so many things, however, the devil is in the details here. The ratio of flash storage to enterprise rotational storage is relatively small — so what’s going on here in terms of performance?

Flash tiered storage is being used to optimize a few attributes of our backup appliances. The first is handling “bursty” incremental backups (sometimes called CBT — or Changed Block Tracking — incremental schemes when talking about VMware vSphere or Microsoft Hyper-V for example) such that the rotational latency and seek times on the enterprise rotational drives are optimized. The second is handling the metadata associated with backup, archiving, replication, and instant recovery. This metadata, which is associated both with granular backup techniques as well as storage deduplication, enable us to scalably handle various types of loads while ensuring that we can handle variable block deduplication from 8K all the way to several megabytes of block size. The bottom line? Faster backups, more frequent backups, faster standard and instant recovery, faster archiving, faster replication — all with superior deduplication so that our customers get more retention in less physical raw storage.


Unitrends has the most scalable data protection (backup) software and physical appliances in the industry. Not by a little — by a lot. Unlike many of our competitors, we don’t have two different data protection solutions — one for SMB and one for enterprise. Instead we cover both. This means that our customers can grow with us as their business (and thus their infrastructure and their data) grows — both by adding new appliances and increasing the size of their appliance to almost 100TB.

In addition, Unitrends supports the concept of hyperconvergence of data protection. This means that we offer not only backup, but archiving, storage deduplication, instant recovery, and other functionality that often takes an enormous processing and I/O load.

Flash tiered storage isn’t used on every one of the Unitrends Recovery-Series family backup appliances — in the low-end it’s not needed. But as the size of the appliance increases in both raw storage capacity as well as in the number of processor cores and memory to do on-appliance instant recovery, the tiered flash architecture we use grows increasingly important in order for us to be able to effectively scale — to handle increasing user demands for functionality on a single backup appliance.


As the amount of raw storage increases, the number of enterprise disk drives increase — which means that the overall MTBF (Mean Time Between Failure) can decrease. By using tiered flash storage, we optimize the I/O characteristics on the enterprise rotational drives to decrease their load.

So that’s it. Performance. Scalability. Reliability. The three primary reasons we included tiered flash storage in our third-generation Recovery-Series appliances. These are available now — and are free to try — I hope you’ll consider us for your data protection needs.


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