Last week there was a floodstorm of articles published around Software Defined Storage, and of course there was the SDS Tweetstorm caused by the NetApp chat (find a summary here and here). One thing that is clear from these articles, and the chat, is that everyone has its own spin around what Software Defined Storage is or should be. Every vendor takes the fairly highly level definition and then molds it in such a way to make it seem they offer a true Software Defined Storage solution today. Personally I will leave that up to you, the consumer, to decide if you agree with them or not… I know that we as VMware are certainly not claiming to have those capabilities today but we are working very hard to get there! Then again, some of my colleagues would argue that Storage DRS, Storage IO Control, Swap to SSD and vSphere Replication are part of that solution.
Anyway, I enjoyed reading these articles, especially back to back as some state the exact opposite around what SDS is. Now as a customer this isn’t necessarily a bad thing as it will offer you choice and various different strategic directions to achieve the same goal: reduce operational complexity and increase agility / time-to-market. I have linked all three articles below with a quote from the article, just take the time read them. Let me know which of the three concepts you liked most… or if you do not agree with either what SDS means to you.
- Nutanix – Software-Defined Storage, Our take!
“A software-defined controller must not use any proprietary hardware. That means no dependence on special-purpose FPGA, ASIC, NVRAM, battery-backup, UPS, modem etc. Use dynamic HTTP-based tunnels instead of modems. Use inexpensive flash instead of ASIC or NVRAM. Use industry standard PCIe passthru if you must bypass the hypervisor.” - NetApp – OK, Sure, We’ll Call it ‘Software-Defined Storage’
“NetApp has been leading the way with storage virtualization for years. If you go back and look at some of our slide decks, as recently as 2011, we were calling Data ONTAP the “Storage Hypervisor,” but we stopped because, at the end of the day, it’s bigger than that. It’s the Control Plane AND the Data Plane. SVM’s (Vservers) are the virtualized part (i.e. Control Plane) and Data ONTAP’s inner workings, APIs, and inter-node communications, and ability to move data around within itself between nodes across a 10GbE highly-redundant cluster network, with little-to-no loss in performance” - HDS – Software-Defined Storage is not about commodity storage
“This has led some analysts to predict that storage functions and intelligence will shift to the server and purchasing will shift to commoditized hardware. On the contrary, storage hardware must become more intelligent to include the storage logic, which can be initiated or automated by events or polices that are defined by application or server software. This has already happened with VMware, as evidenced by the company’s motivation to off load server functions to storage systems through APIs like VAAI and VASA in order for VMware to be more efficient in supporting virtual machines. This requires more intelligence in the storage to support these APIs and provide visibility through vCenter.”
** The NetApp article is an article by Nick Howell on his personal blog and doesn’t necessarily 100% align with NetApp’s vision. Considering Nick works at NetApp in the Tech Marketing team it probably represents their view **
I think HDS’s article is the closest to my view of SDS. I do not think that storage will be commoditized entirely as storage vendors will continue to offer their own capabilities into the stack. It is also right that the different capabilities will be governed from software using policies. The only thing i would add is that the virtualization layer can and will offer their own storage capabilities and will allow the customer to choose to use what fits his environment the best, freedom of choice with a single policy driven management is SDS in my view. What VMware offers today is not yet SDS but is the way to it, to achieve real software defined we will need to have a common language between the different components virtual and physical and that takes time and cooporation, VAAI, VASA, SDRS etc are part of that journey.
I think HDS is right and NetApp too ; NetApp doesn’t do it on commodity hardware either.
HDS – VSP – is the only Enterprise Storage Platform to offer “Controller Based Virtualization” and “Read / Write Cache Mirroring” Only vendor with intelligence to distinguish between read requests and write requests –
Controller based virtualization offers a unique benefit where when you virtualize – say an old array behind a VSP, all features offered by VSP will be made available to the Storage being virtualized. for e..g VAAI, if your OLD array doesn’t support VAAI, but you have virtualized it with a VSP, you will then be able to utilize VAAI on that storage as well – quiet cool !!
NetApp (my favorite too) : is extremely flexible, user friendly and does SDS as of today – !