Question

What is Storage Spaces Direct (S2D)?

Answer 1

Requirements for Storage Spaces Direct (S2D)
What is the composition of Storage Spaces Direct (S2D)?
When is Storage Spaces Direct (S2D) used?
How does Storage Spaces Direct (S2D) work?
How does Storage Spaces Direct (S2D) protect against drops?
Summary of Storage Space Direct (S2D) Benefits
Correct Selection of Hardware Components for Storage Spaces Direct (S2D)
Network infrastructure for Storage Spaces Direct (S2D)

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What is Storage Spaces Direct (S2D)?

At some point, all hard drives end up filling up. Storage Spaces Direct is a method of logically joining multiple hard drives to appear as one large drive to the user. The user no longer has to worry about the physical location of storing their data, as the servers manage the S2D file system automatically. This system requires a very high reliability against falls from the components used..

Storage Spaces Direct, in Spanish, direct storage space, allows the data carriers of different Windows servers to be grouped into a single storage cluster that is then divided into logical disk units that are enabled for users. In this context, the software is in charge of controlling the disk drives, which implies certain requirements when choosing the hardware.

Index

1. Requirements for Storage Spaces Direct (S2D)
   1. Correct Selection of Hardware Components for Storage Spaces Direct (S2D)
   2. Network infrastructure for Storage Spaces Direct (S2D)
2. What is the composition of Storage Spaces Direct (S2D)?
3. When is Storage Spaces Direct (S2D) used?
4. How does Storage Spaces Direct (S2D) work?
5. How does Storage Spaces Direct (S2D) protect against drops?
6. Summary of Storage Space Direct (S2D) Benefits

Requirements for Storage Spaces Direct (S2D)

Storage Spaces Direct (S2D) is a type of Windows Server 2016 software-defined storage , so it cannot run on any Windows computer. The technology is based on the storage spaces that Microsoft introduced already in Windows Server 2012, back then, still with the Scale Out File Server (SOFS), a scale-out file server..

Using Storage Spaces Direct (S2D) requires multiple hard drives on a server or multiple servers with one or more hard drives each. Servers can be connected via Ethernet , so no special cables are required. Classic hard drives (HDD), SSD or NVMe memory cards can be used as disk drives.

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Storage Spaces Direct is abbreviated? S2D ?. This is mainly due to the abbreviation? SSD? it already exists. SSD stands for Solid State Drive, a well-known type of semiconductor storage. For users, SSDs look the same as disk drives, but unlike hard drives, they don't use mechanical components..

Correct Selection of Hardware Components for Storage Spaces Direct (S2D)

For the hardware components to interact in a harmonized way, all Microsoft computers and drivers require a Windows Server 2016 certificate to use Storage Spaces Direct. Microsoft has a list of preconfigured servers from different vendors. All of them meet the requirements of Windows Server 2016: Hyperconverged Systems. Another possibility is to assemble the appropriate components on your own. In this case, you must use components certified by Microsoft's Software-Defined Data Center (SDDC).

The Intel Nehalem, or the similar AMD EPYC, meets the minimum requirements for processors used in servers. In addition to the storage space required by a Windows server that meets the same requirements, a Storage Spaces Direct node requires 4 GB of RAM for each TB of disk drive cache.

The hard or SSD can be connected via SAS or SATA. USB drives are not supported and RAID controllers cannot be used as hardware activation is done exclusively through the Storage Spaces Direct software layer. The disk drives must be physically connected to the server, it is not possible to integrate network storage spaces (NAS, Network Attached Storage).

To save frequently accessed or modified data, it is best to use SSD on servers. In this case, you should use Enterprise SSDs that are compatible with Power Loss Protection , that is, one that does not generate file system errors in the event of a power failure. When using SSD or NVMe, all mounted disk drives must be in a node of the same type.

Network infrastructure for Storage Spaces Direct (S2D)

To allow communication within a cluster, the different nodes must be connected by at least a 10 GBit network . The network cards used must be compatible with RDMA (Remote Direct Memory Access) with the RoCE or iWARP protocols. When connecting workstations to the network, the usual Windows Server networking specifications apply.

What is the composition of Storage Spaces Direct (S2D)?

Direct storage spaces consist of at least two nodes. These nodes are standard Microsoft-certified server hardware running Windows Server 2016. Each node has a minimum of two mounted disk drives. You must install the Failover Cluster Feature on Windows Server 2016 to protect against hardware failure.

S2D forms a storage-capable cluster of elements that can then be accessed by, for example, different virtual machines.

When is Storage Spaces Direct (S2D) used?

Direct Storage Spaces are perfect for flexibly increasing network storage capacities and ensuring high data security in the event of hardware failures. In this way, data is available simultaneously at different locations in the company, as long as there is a fast network connection between the locations.

Another area of ​​application is the virtual machines based on Hyper-V technology in the network, since with Storage Spaces Direct they can be scaled more easily. In this way, multiple virtual machines can access the same data.

How does Storage Spaces Direct (S2D) work?

Storage Spaces Direct (S2D) is a software-defined storage solution in which software manages the hardware storage media. Thus, the storage capacities and technical advantages of different data carriers can be centrally grouped, even if they are connected to different servers in different spaces. In this way, the server and media are grouped together in a Storage Space Direct Cluster.

If different storage technologies are used, the software automatically decides which data is stored on which hardware. Frequently accessed files are stored on fast NVMe media, frequently modified files are stored on SSDs, and infrequently accessed data and backups are stored on classic hard drives.

As cache memory, SSD or NVMe media should also be used wherever possible. Network users see the entire Cluster as a single enabled network element . They don't have to worry about what data is on what hardware.

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IONOS Enterprise Cloud also offers software-defined storage technology to small and medium-sized businesses that do not have their own server. In this commercial cloud you can scale the resources you need on your own and at any time with the Data Center Designer.

Administration is carried out on the server, using the graphical tool? Server Manager? Windows Server 2016 operating system or through the command line. During the installation of the Storage Space Direct Cluster, first of all, all the hard drives of the different servers are grouped in a Storage Pool . It is important that only those disk drives that contain user data are integrated into the cluster. The server operating system disk drives remain independent.

Suitable hard drives and semiconductor storage media are automatically detected and added. In this way, later, more hard drives and servers can be integrated into the cluster to scale the storage capacity as needed . Each node supports four data disk drives and two cache disk drives in addition to the system hard disk.

Virtual disks are created in the new cluster and are here called Cluster Shared Volume (CSV). These CSVs are then formatted, a process that allows for two file systems. Microsoft recommends CSV-ReFS (Resilient File System), because it is better suited to Storage Spaces Direct technology than CSV-NTFS, based on the classic NTFS for hard drives. CSVs can span multiple hardware disk drives, but this does not affect the user since they are all managed by the system.

Each Storage Space Direct node can reach a total storage capacity of up to 100 TB. A multi-server Storage Pool can only use a maximum capacity of 1 PB (PetaByte = 1024 TB), even though Storage Spaces Direct (S2D) allows up to 16 servers.

The network communication between the different nodes is done through the SMB3 protocol , an evolution of the Server Message Block (SMB) with SMB Direct and SMB Multichannel.

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It is also possible to join multiple hard drives into a single drive on a conventional Windows computer. In this case, the solution is dynamic data carriers . In Windows 10 data carrier management, existing hard drives can be turned into dynamic data carriers. These media can then be grouped into a logical disk drive. Mirror copies of the data can also be made automatically. However, without a new format, there is no going back.

How does Storage Spaces Direct (S2D) protect against drops?

Through the Windows Server 2016 Failover Cluster Feature , Storage Spaces Direct provide a number of measures to protect stored data against hardware failure. In this way, if there is a failure of a hard disk or an entire node, no data is lost and the system continues to function as a whole. In most cases, users are not even aware of the hardware failure.

When a cluster consists of only two nodes, two-way mirrors are created that synchronize the data from both nodes, so that a node or a hard disk can completely stop working without causing any problems. Starting with three nodes, it is recommended to do a three-way mirroring .

In the latter case, there is no problem if one of the three nodes stops working completely and in another there are several hard drives that are not working. However, more than half of the total data disk drives should never be affected, since then, data consistency is no longer ensured. This rule does not apply to operating system hard drive failures, as these are equivalent to a server failure.

Summary of Storage Space Direct (S2D) Benefits

• Good scalability , more servers can be added without problem.
• High availability thanks to mirror copies of the data ; hardware failures do not mean any data loss.
• Unlike similar solutions from other manufacturers, you can use standard server hardware as long as it is certified by Microsoft.
• The system has been optimized for SQL servers and virtualizations with Hyper-V.

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