Hyper-converged storage architectures (Draft)
Executive Summary
Hyper-converged storage architectures from Microsoft reached maturity in 2019, becoming a CIO’s best bet for initiating high availability services built upon direct-attached commodity storage devices that are managed directly by the OS (i.e. S2D).
Creating server architectures with multicore CPUs, large amounts of RAM, and a mix of locally attached storage (NVME (PCI bus) Disks (SAS),IDE, FC) reflects a (not totally) new category of server architecture, known as “Converged’ or “HyperConverged”. S2D is the MS’ designation for a software defined storage architecture that manages direct attached commodity storage devices via a unified OS management console (Windows Admin Center), which Microsoft trumpets at every opportunity on Technet video, seemingly deservedly so.
The Reality Check
S2D has, in 2020, overcome the market’s adoption hurdles. One facet of general acceptance is MS joining the rest of the storage OEM market. leaving RAID (mostly)behind and moving the management of mass storage into the OS. This trend started before Sun and ZFS, and subsequently grew into an industry. The enthusiasm for S2D is further borne out by the hardcore MS critics and analysts giving positiave voice to S2D, and finally, name-brand VARS and OEM vendors such as DellEMC and HP are offering off-the-rack S2D server nodes. These solutions are conspicuous in the Windows hardware catalogue, and that is an endorsement.
The licensing conundrum
Microsoft’s licensing intent is less than crystal clear in the case of S2D – which most catalogs state as “Data Center” licenses only; other articles and forum responses from authorized representatives and VARS state that, “S2D may be used in any standalone Windows standard server without Data Center Licensing.” So this is a matter for continuing research.
The confusion is typical. “Storage Spaces” is for standalone control of local storage (starting in Server 2012) , Storage Spaces Direct (S2D) may span multiple nodes, even spanning WAN based and cloud nodes, starting with Server 2016 Datacenter license only.
This causes a great deal of frustration for IT professionals. Fortunately converged storage solutions have been around prior to S2D, even as MS partners. One MS partner has been offering HCI since 2015 and before, even some free VSAN solutions, and now off the shelf using either Dell or Supermicro hardware.
Competitive Alternatives
While quotes slowly trickle in from the vendors (Dell, HP) , let’s talk about Starwind, a local MA company. Starwind was chosen as a storage vendor at Loren Data Corp in 2015, when I participated in specifying mirrored server hardware, working alongside the President, Todd Gould, a Database expert. Starwind was mentioned in several Technet blogs and articles, early on during the maturity cycle of Storage Spaces and most pointedly, S2D.
Starwind started as a featured microsoft partner, and feature for feature, it seems to lead Microsoft’s offerings by a year or so. These mentions by Technet and the feature parity to S2D, could possibly mean a technology sharing partnership that lasted at least until 2019.
Articles by Starwind technical marketing (Anton Kolomyeytsev) are really worth reading for a proper understanding of converged servers.
The bottom line from reading the most recent Starwind and Microsoft articles, is that RDMA and SMB 3.1 are the enabling technologies that make converged storage using S2D or the Starwind VSAN practical, cost effective, and easy to use.
It has been a long time since a high-payoff technology has shown up that performs in a demonstrable fashion, as the live videos of S2D installs, most no more than 15-20 minutes, show how much polish MS has invested since 2012 in storage Spaces and Storage Spaces Direct.
What does all of this get us?
Familiar server components are converging or being moved out of the server tier. In the present case, hyper converged compute / storage leads to elimination or reduction of RAID or external SANs. Microsoft’s success in S2D shows in the very widely reported ease of creating and managing virtual machine instances, clusters of storage composed of direct attached SSD, SAS, IDE.
By eliminating the RAID and SAN enclosure abstraction layer (the black boxes), S2D lowers storage hardware costs while reducing management headaches – by presenting a unified interface, rather than proprietary software layers. Eliminating Storage Tier Complexity reduces drive rebuild and cluster recovery times, which increases availability.
Is it a good thing?
Storage Spaces Direct brings this all together within High Availability, failure tolerant infrastructure which encompasses Disaster Recovery, if desired.
The resulting IT Press coverage of S2D has been enthusiastic , especially in the 2019 server incarnation. Analysts have stated that S2D may be Microsoft’s most important contribution to server-based computing in the post-cloud computing era.
Is this good?
If the idea of Converged server architecture is appealing to any IT management, then a decision will need to be made on server licenses – Data Center is not an inexpensive license, although it offers a tremendous amount of Hyper V flexibility. Combined with S2D, it’s a killer package – unlimited VMs, converged storage with fault tolerance and freedom from RAID with all that means.
Further Reading
https://www.petri.com/what-is-microsoft-storage-spaces-direct
https://www.virtualizationhowto.com/2017/09/differences-storage-spaces-storage-spaces-direct/
A very recent hands-on article from the System Center Team is very worthwhile reading:
Cost, licensing, details
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