Thanks to VMware’s vision on software-defined data center (SDDC), software-defined anything is one of the leading buzzwords today. Software-defined storage (SDS) is not an exception. SDS feels like a big shift in storage world, but good news is that the transition is much smoother than it sounds. Let us take a closer look. What is SDS? There are many vendor specific definitions and interpretations for SDS. Industry analysts have their own versions too. Hence let us focus on what matters the most. The characteristics and benefits expected in general from SDS. There are the four pillars.
- Abstraction:Data pane and control pane are separated. In other words, the storage management is decoupled from the actual storage itself. Customer benefit: flexibility to solve for storage and management needs independently
- Backend heterogeneity: Storage is served by any kind of storage from any vendor including commodity storage. Customer benefits: Freedom of choice for storage platforms, avoid lock-ins.
- Frontend heterogeneity:Storage is served to any kind of consumers (operating systems, hypervisors, file services etc.) Customer benefit: Freedom of choice for computing platforms, avoid lock-ins.
- Broker for storage services: SDS brokers storage services, no matter where data is placed and how it is stored, through software that in turn will translate those capabilities into storage services to meet a defined policy or SLA. Customer benefits: Simplified management, storage virtualization, and value-added data services through vendor or customer innovations.
Three out of four pillars are needed to qualify as a software-defined storage solution. Pillars 1 & 4 are must haves. Once you have those two you need 2 or 3. The reality is that SDS movement had started long time ago. Let us use some examples to understand the SDS implementations.
Oracle Automatic Storage Management (ASM): Although Oracle seldom markets ASM as an SDS solution, it happened to be a great example of SDS. It is purpose-built for Oracle databases. It features all the four pillars and storage is entirely managed by the application owner (Oracle DBA). The pillar 2 is questionable here. It does have that pillar because the solution runs on multiple OS platforms. However it serves just one type of workload, hence that pillar is not truly delivering frontend heterogeneity.
Veritas InfoScale: Formerly known as Veritas Storage Foundation, Veritas InfoScale is perhaps the most successful, heterogeneous, and general purpose SDS solution. While it is still widely in use, it is a host based SDS solution (the pillars are built on top of the operating system) and hence not a good fit for virtualized world.
VMware Virtual Volumes (VVOLs): VMware VVOL is purpose-built for VMware vSphere. Hence it lacks pillar 3. VVOLs shine well with the other three pillars. A virtual infrastructure admin could manage everything from a single console.
Now that we covered the characteristics of SDS, let us look at the bigger picture as an IT architect. The great thing about SDS solutions is the interoperability to build the right solution for workloads so as to solve for constantly changing storage needs. You can be quite creative (and of course, even go crazy!) with the type of things you can build with SDS Lego blocks.
You can deploy Oracle ASM on top of Veritas InfoScale so that DBAs could benefit from both. ASM enables Oracle DBAs to manage their storage while InfoScale brings centralized management for storage administrators.
How about that virtual server environment where Veritas InfoScale is falling short? Bring in storage LUNs directly into vSphere hosts for a VMFS experience where they enjoy the benefits provided by VMware. Are virtual machine infrastructure administrators getting ready to manage storage on their own? Give them the array plugin for VMware vSphere Web Client. Or prepare them for VASA provider from storage vendor to get ready for VVOLs!
The main takeaway is simply this. SDS is a blessing for IT architects to solve storage puzzles elegantly. It had been here for long time, it is also constantly evolving with market inspired innovations. Transitioning to SDS is relatively smooth.
Disclaimer: The opinions here are my own. It does not reflect those of my current or previous employers.