Educational Episodes: Hyperconverged Infrastructure (HCI)

This is a short summary on Storage Spaces Direct – the first true software-defined storage from Microsoft, its history and peculiarities. Software-defined storage is a concept, which involves storing data without dedicated hardware. This is an introduction to a series of posts dedicated to theoretical and practical research of S2D. The post is not a full description of the Storage Spaces Direct technology, more info is available on Microsoft resources. Our focus here is the actual problem that S2D solved for virtualization world, being truly independent from underlying hardware, as SDS should. Its predecessor, Clustered Storage Spaces, had a very serious hardware lock-in with its requirements for SAS fabrics, SAS switches and SAS JBODS. Thus, Storage Spaces Direct is an interesting technology to research.

Log-Structured File System is obviously effective, but not for everyone. As the “benefits vs. drawbacks” list shows, Log-Structuring is oriented on virtualization workload with lots of random writes, where it performs like a marvel. It won’t work out as a common file system for everyday tasks. Check out this overview and see what LSFS is all about.

The post describes the history of RAID 5 and how it became obsolete at some point in time, just because HDD capacity grew at an enormous rate. It happened due to the chance of failure that grew to literal imminence when spinning disks reached TB scale, because the reading speed still had the same physical limits. Basically, creating a RAID 5 even with 1 TB disks would mean certain failure of the whole array and quite soon. The array technology was “saved” by an unlikely ally – the SSD. Being faster than hard disk drives in everything, they almost nullify the chance of the abovementioned failures. The post is written for everyday reader, not just engineers, and is quite comprehensive even without special knowledge and skills.

Here is a comparison of two technologies with similar task but different methods of accomplishing it – Link Aggregation Control Protocol (LACP) and Multipath I/O (MPIO). Both are aimed at providing higher throughput when one connection can’t handle the task. To achieve that, LACP bundles several physical ports into a single logical channel. MPIO, on the other hand, utilizes more than one physical path, even if the working application does not support more than one connection. Both technologies seem to be equally effective at first glance, but further study confirms that one of them is better at achieving its goal. The post is practical, so expect detailed research with screenshots and complete analysis of the technologies in a test case.

This research is, basically, an answer to some statements about NFS shares and Hyper-V Virtual Machines that StarWind engineers considered false. Hyper-V is a native hypervisor from Microsoft and one of the most popular ones. It is capable of creating virtual machines on x86 and x64 Windows systems. Microsoft suggests that VMs should be stored in the Cluster Shared Volumes, in case live migration and failover are required. Storing them on an NFS share was never present in the design, so StarWind team was a bit skeptical about the idea at the first place. This research contains the full experiment, aimed at proving or disproving the initial statement, complete with a few different checks. The result is quite an expected one, but nevertheless, curiosity is strong in StarWind engineers.

There is a new feature in Windows Server from Microsoft, called Soft Restart. The idea itself is perfect, because its goal is to minimize downtime during reboot process. While it is possible to reduce software starting sequence time, when starting the hardware there are physical time limits. These limits made it impossible to reduce reboot time, before Microsoft thought about the “soft restart”. It is claimed to perform standard reboot without restarting the devices, basically resetting only software and reducing the required time dramatically. StarWind engineers decided to check if Soft Restart works fine in two use cases – with a simple physical setup and with virtualized infrastructure. As it always goes with our practical approach, the fool experiment complete with screenshots is in the post.

This post is about Microsoft Storage Replica, a new solution introduced by Microsoft in Windows Server 2016. Basically, it enables replication between two servers, clusters or inside a cluster, also being capable of copying data between volumes on the same server. Storage Replica is often utilized for Disaster Recovery, allowing the user to replicate data to a remote site, thus being able to recover from complete physical failure on the main location. The post is dedicated to building a “shared nothing” cluster. It is an experimental part of a series and features a “Shared Nothing” Hyper-V guest VM cluster. As always, there is a detailed instruction as to how to create the subject setup and there are results for everyone to check.

This post is dedicated to the new solution from Microsoft – the Microsoft Storage Replica. It is a practical part of a series of posts about this technology and features a “Shared Nothing” Hyper-V HA VM Cluster in practice. Microsoft Storage Replica is designed to perform replication between various media: servers, clusters, volumes inside a server, etc. It’s typical usage scenario is Disaster Recovery, which is essential for data protection in case anything happens to the main location. Critical data is replicated to a remote site, often located hundreds and thousands of miles away for better data safety. The experiment is performed by StarWind engineers, so the post contains detailed instructions and a comprehensive conclusion.

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