Hybrid, flash, converged storage, what’s next? Hybrid storage stack!?

I saw a tweet pass by from PernixData and although I already knew the world of datacenter/storage design was changing it just really sank in. Over the last 5 years we have seen the world of storage change significantly. We have seen new types of storage being introduced like all-flash-based storage, hybrid storage (mix of SSD and SATA) and hyper-converged solutions. Examples of these would be Violin Memory (all-flash), Tintri (hybrid) and Nutanix (converged). More recently object-based storage solutions are trending, as Stephen Foskett states in his article on scaling storage it is nothing new but it seems to be more relevant in this new day and age.

I would expect Frank Denneman to dive in to the whole architecture aspect as part of his “Basic elements of a flash virtualization platform” series, so I am not going in to a huge amount of depth, but I did wanted to coin this term / strategy / direction. Host based flash caching solutions like VMware vFlash (when released), PernixData, FlashSoft and others will allow you to decouple performance from capacity. It truly should be treated as a new tier of storage, an extension of your storage system! This is something which will take time to realize… as it is natural to see host based flash caching solution as an extension of your hypervisor. I have been struggling with this myself for a while to be honest. When you realize that host based flash caching is a new storage tier you will also wonder what would sit behind that new storage tier? In an existing environment it is clear what the next tier is, but in a green field deployment which components should be part of a hybrid storage stack?

Just to clarify, “hybrid” in “hybrid storage stack” refers to the usage of flash for performance requirements and spindles for capacity whereas “stack” refers to the fact that this solution is not contained with in a single box as opposed to a hybrid storage device. So the first component obviously would be host based flash caching, this would enable you to meet your performance requirements. Now, I will aim to keep things simple but there are various host based data services like replication which could be included if needed. From a capacity perspective a storage system would be needed, something that can easily scale out and is easy to manage. Object-based storage solutions are trending for a reason, and I think they could be a good fit. No need for me to explain why, when Stephen has already done that in his excellent article, lets just quote the relevant portion:

This is exactly the architecture that the latest storage arrays are adopting: Object storage inside, with loosely-coupled nodes offering truly dynamic scaling. Although many allow native API access, most of these products also include an integrated object-to-file gateway, with VMware-friendly NFS or Windows-oriented SMB as the front-end protocol. These aren’t the ideal protocols for scaly-storage access, but at least they’re compatible with existing applications.

By finally divorcing data storage from legacy RAID, these systems offer compelling advantages. Many include integrated tiering, with big, slow disks and flash storage acting in concert.

Now here comes the problem I see… These object storage solutions today are not designed to work in-conjunction with host local flash caching solutions. Not that I would expect it to cause issues from a technical perspective, but fit might cause issues from a total cost of ownership perspective. What I am saying is that many of these systems are already “optimized” for both performance and capacity. So what would be next? Smart object based storage solution that integrates with host local flash caching solutions and can easily scale out for a fair price? I haven’t seen too many (which doesn’t mean there aren’t any), it seems there is an opportunity here.

Maybe a call-to-action for all those vendors working on host based flash caching solutions… It would be nice to see reference architectures for existing environments with legacy storage, but also for green-field deployments. What if I have a brand new datacenter, where does your platform fit? How do I control cost by decoupling performance and capacity? What are good options for capacity? How well do these solutions interact / integrate? I know, a lot of questions and not a lot of answers for now… hopefully that will change.

Be Sociable, Share!


    1. says

      Hi Duncan,
      I am a long time follower. I jumped on the vmware band-wagon circa vcenter 4.0. I really believe in your vision of software defined storage, so much so that I quit my day job and started my own consulting firm specializing in VMware converged storage using VSA. After 15 years in the IT industry, this was my chance to sink or swim and I think my timing could not have been better. I completed my vmware class and passed the VCP exam late last year.
      I am working with Acer to build a 3 host VSA cluster at an affordable price, to allow public libraries, two of whom I support, to enter the world of virtualization and VDI at a 20k price with software, hardware, and my cut included.
      I am working with Acer via RDP to their data center in California, and they are swapping parts as I hit bottlenecks in the system.
      I explained to them, that there has to be a balance between cpu cycles, available usable storage, and storage iops, and all three should run out at about the same time, only then have we found a good affordable balance to a converged storage cluster at an affordable price.

      I hope in writing the Tweet sized vSphere Design Considerations, someone looks at VSA. I truly believe VSA is the future for a SMALL business with around 25 to 100 users, my target market. From what I have seen so far, big consulting companies arrive to quote such customers 40k price tags for tier 1 hardware and EMC VNX storage [I am a partner], when all they really need is a simple 3 host cluster, with Vcenter ESS Plus maybe Veeam backup, for 20k, with VDI for their back office pc’s.
      I wanted to thank you for running such a great blog, I have it set to my home page and I read it every morning with my coffee.

      Thanks again,
      Virtually-Green Computer Solutions

    2. says

      Fantastic Post! A while back I had planned to test perf vs cost in offering Flashed based storage as a performance based tier in a Virtualized Hosted Datacenter env. This would be an additional cost to a tenant but I figured they would find it valuable enough to justify the additional cost because certain workloads would need it. I guess you could think of it as Flash-as-a-Service. So if we add your latest brew into the mix, and lets say there is a vendor who figured out how to converge these technologies to service a tierd or profile driven approach to fine tune your FaaS, would the cost to the provider really matter if their tenants wanted to consume it? I know as a provider you try to keep costs down so you can offer the lowest price point to the customer, but in IMHO if you inclued higher, more costly options, such as what you are asking , there would be enough consumed to cover cost of purchasing and operations for the provider.

      This also begs the question about Flashed backed Virtual Mahines.

    3. says

      Oh. And whole flash storage solutions could be just what’s needed to remove latency in nested hypervisor environments and bring them up to first class citizens.

    4. says

      Great post Duncan. I just wanted to pose a question/comment pertaining the need for integration with local host caching and arrays. Wouldn’t we want that integrated in the vSphere stack as a software managed solution? I could see this working with some of the integration of plugins, etc from storage vendors today, but much more tightly integrated. While we don’t want to take ‘complete’ management control away from the storage array vendors, you would think that the control should take place within the Virtual Stack. In essence, my hope is that vSphere can manage any storage solution and just see it as available disks, much like vSAN will see local storage on the hosts.

    Leave a Reply