UnityVSA: An Introduction to Software Defined Storage

Disclaimer: I am an old school EMC guy, I cut my teeth on Clariion, Celerra, and VMAX. I am EMC ISCA certified. I worked for several managed service providers (MSP) in my background where I provided enterprise customers with storage advice and support. That means that while I had many customers that used all kinds of storage equipment (Netapp, Hitachi, 3Par, etc) and I had to support whatever they used but when consulted I would generally steer customers into an EMC solution if it made sense for their environment as they are a market leader and I am very familiar with their equipment capabilities and limitations. My other favorites are Pure Storage, Infinidat, and Cohesity but those vendors should be covered in another article..

I have to admit it, I love new EMC Unity! With it I think EMC fixed all of my gripes about their aging VNX platform. From my experience its capabilities outshine its competitors like the HPE 3Par and Netapp AFF. They sell Unity as a traditional hardware storage array either hybrid or all flash and they also offer it as a software defined storage virtual machine edition if that fits your use case. In fact they offer a community edition license on the virtual edition for free! How cool is that, you can get an enterprise worthy virtual NAS solution for your home environment for free (up to 4TB capacity)? The physical arrays and the virtual use the exact same code on the back end. The platform is so embarrassingly user friendly to configure I think it is going to put a lot of dedicated Storage Admins out of a job or at least give a lot of general linux and windows system administrators the confidence to administrate this machine without special training. It has all kinds of great value added features that the competition lacks like the integrated data migration tools that I plan to cover in future articles.

But what is software defined storage?

In layman's terms, the premise of software-defined storage is to take the software that used to run inside a SAN storage array and offering it as software for deployment anywhere. Instead of purchasing a traditional dedicated storage array, you can use software that can run on any x86 server virtually. The storage becomes a heterogeneous pool of hardware resources and the “where” no longer matters, so long as the data is stored somewhere. Migrating your data to faster or cheaper disks or even to a cloud provider can now be accomplished by a simple "vmotion". Since most enterprises are still leveraging in house virtualization, forget thinking of this technology as the data center of the future, this can be done with is the data center of today.

The multi-protocol problem...

But why do we need a fancy Dell appliance to do this? Couldn't you just create a linux virtual machine to act as a samba file server or use some FOSS NAS distribution like OpenMediaVault or FreeNAS? Of course you could. If you dont need the support, the stability, the scale, or the migration and replication features I can think of one killer feature that you cant get with a FOSS solution. Heterogeneous OS read and write access on the same file system. You see, many vendors (I am looking at you HPE 3Par) wont even allow you to have both linux and windows clients read and write to the same NAS file system. So if you create a new NAS file system and set up the share as Read/Write SMB then you can only allow NFS to be read only or vis-versa. Other vendors may allow you to actually setup the share for multiprotocol/multi OS access but you will quickly find out that the file permissions get destroyed and overwritten. The problem is Windows ACLs and POSIX mode bits are not inherently compatible with each other so they constantly fight for supremacy. Windows will ignore the POSIX mode bits and linux will ignore the windows ACLs. To actually do this gracefully you need to have support for multiprotocol/multi OS access baked into the file system. As far as I know, EMC and Netapp are the only vendors who have products that even support this. Unity supports this out of the box if you set up the file systems correctly but so does Isilon. Below I have linked a short EMC presentation video for Isilon describing the problem more in depth. Although Isilon's method for overcoming this issue is different (some ways more powerful) the problem is the same.

In this multi-part guide I will walk you through deployment and configuration of a Unity VSA both as a multi-node HA cluster and as a single node free community licensed machine that is suitable for your homelab or even a small organization. Along the way I will ensure it is set up according to industry standards best practices for mixed OS file workloads and pass along some pointers that I have learned in the school of hard knocks. I hope you give this platform a chance and fall in love with it like I have.

In part 2 I will cover deploying Unity VSA to a local vCenter environment.