Most IT vendors like to jump on the “latest bandwagon” to showcase their solutions, they then use key IT buzzwords to highlight their product as being cutting-edge. One of the most prevalent in today’s technology world is Software-Defined, but there is significant ambiguity with regard to exactly what it means.
So what is my definition of a Software-Defined solution?
You purchase software and hardware independently, more often than not from different vendors, and most importantly you can change the hardware without incurring additional licence fees – examples include VMware vSphere, Veeam Backup and Replication, and CommVault Simpana.
So what is my definition of a non-Software-Defined solution?
You purchase a hardware appliance that combines software and hardware into a single solution (you cannot move the software to different hardware) – examples include storage arrays and purpose-built backup appliances.
So based on these definitions:
- Virtual SAN is Software-Defined Storage
- Virtual Volumes is not Software-Defined Storage as it is Virtual Machine centric policy-based storage management, that does not provide any storage services, but it is part of a Software-Defined solution (vSphere)
- EVO:RAIL is not Software-Defined Storage as it is a hyper-converged hardware appliance
It would say that VMware NSX is Software-Defined Networking as it provides networking services that can use any networking hardware as the transport mechanism.
I cannot see how anyone can argue against these definitions, but I know they will.
Is Software-Defined better than non-Software-Defined Storage?
Absolutely not, but Virtual SAN has advantages:
- Utilise commodity hardware – that is typically very cost-effective
- Increase performance and capacity – just by changing the hardware
- Lower ongoing costs – once the license is purchased only annual maintenance is required (no need for a complete array refresh)
- Gain new features – just by upgrading the software (arrays will often require new hardware to run the latest software)
- Simplified management – compute and storage are managed together
Equally there are many advantages of a storage array:
- Proven – leading arrays are very mature as hundreds of thousands of units have been shipped with advanced data integrity features that deliver 99.999%+ availability
- Double disk protection – whilst this is supported on Virtual SAN it is almost certainly not practical at scale
- Flexibility – with support for vSphere and any other hypervisor or physical server, independent scaling of storage and compute, and support for multiple disk tiers
- Usable capacity – using parity RAID/Erasure coding usable capacity ratios of 80% can be achieved
- Rich data services – most storage arrays include de-duplication, compression and tiering, and some include NAS and integrated data protection along with many other advanced features
- Replication – many storage arrays support synchronous and continuous availability solutions
- Turnkey solution – with a single contact for support of all hardware and software
- Cost – a low end array will be less expensive over a 5 year period
As can been seen above there are significant pros and cons of each type of solution, so customers need to decide on a case-by-case basis which is best for them.
Now VMware make a big thing about the key selling point of Virtual SAN is that you do not need a dedicated storage administrator, as you can use the Storage Policy Based Management (SPBM) framework to provision VM storage, but you still need a vSphere administrator who understands storage.
Most modern storage arrays are fairly simple to deploy and with Virtual Volumes things are only going to get a lot easier – the storage administrator presents large pools of storage to the vSphere administrator, who uses the same SPBM framework to provision VM storage – therefore Virtual Volumes removes one of the biggest advantages that Virtual SAN has over a storage array.
What do you think – does the industry need to stop using the term Software-Defined when it does not make sense and is the future purely Software-Defined or will we continue to mix and match hardware appliances with software-based solutions?
Related Posts
- VMware VVOLs on NetApp FAS is now available to deploy
- A deeper look into NetApp’s support for VMware Virtual Volumes
- VMware changes EVO:RAIL licensing but still gets it all wrong
- An introduction to VMware NSX Software-Defined Networking technology
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