November 2022 David Chu
Hyperconvergence is a rapidly growing storage segment. More and more companies are choosing to move from traditional architecture to HCI. Do you want to know why? In the article, we will answer this question and tell you what tasks vSAN is suitable for on the example of a solution from VMware.
Traditional architecture has proven itself over many years of its existence, it is reliable, practical, and versatile. All three of its components, namely servers, data storage systems (DSS), and storage networks, interact at high speeds and provide good fault tolerance, but its construction, maintenance, and scaling is a task of a long time and big money.
When the result is needed quickly, and in today’s business, cloud or otherwise, the need for computing is changing very dynamically – the “bricks” of converged systems become more convenient. Therefore, if you are building an infrastructure for resource-intensive business tasks or planning to scale it, pay attention to HCI.
VMware proposes to combine both compute and storage functions on one device – to deploy a converged software solution VMware vSAN. Such a converged storage system does not require special devices and data transmission networks, it works directly on the server and is able to perform the same task as an external storage system.
VSAN uses the server’s disks to create virtual storage that is available to all nodes in the vSphere cluster. Programmatically, this works on the same hypervisor as the virtualization platform itself, in parallel with the computing part. Accordingly, both virtual storage and virtual servers work simultaneously on server – convergence. For fault tolerance, several nodes are needed, the disks of which will create a single storage space available even in the event of a failure on one of the servers.
Each host (cluster node, server) is part of the overall vSAN cluster and must have at least one disk group. The disk group consists of 1 cache disk (fast SSD) and 1 to 7 storage disk (regular HDD or also SSD). There can be up to 5 such groups on a server, therefore, the maximum amount of storage on one server will consist of 35 disk capacities, and the minimum one.
In order for a vSAN cluster to work, a minimum of 2 hosts is required, the disk groups of which will be mirrored to ensure continuous operation in case of failure. This configuration only works with the Mirroring fault tolerance method (similar to RAID1). In it, the Number of failures to tolerate parameter is equal to one, that is, data from one host is immediately synchronized on another. By adding another host and setting the FTT=2 parameter, the data will be replicated on two servers, which increases the degree of fault tolerance, but makes the use of disk space even less efficient. The maximum value of FTT=3 allows you to have data instances on 4 different hosts.
If you are using an All-Flash configuration, that is, only SSD drives are installed on the nodes, then you can use the Erasure Coding method (similar to RAID 5/6). Writing to disk groups is accompanied by the calculation of the corresponding parity blocks, which allow you to recover data in case of failure. So you can significantly save disk space but lose in speed and recovery time. The minimum number of hosts required for Erasure Coding to work is 4, but 5 to 7 is recommended.
The standard vSAN organization option uses hosts running ESXi hypervisors, but vSAN Appliance and Storage Appliance solutions are possible. With vSphere installed, you can activate vSAN without additional plug-ins and add-ons, and all management is performed from vCenter.
Successful implementation of vSAN depends on many factors, but there are basic requirements and features that you need to know in order to avoid mistakes.
Using vSAN reduces costs, and provides flexible scalability and easy management of a single VMware ecosystem. HCI solutions are at the peak of popularity, this is due to their versatility and speed of implementation. Businesses require instant response to change and converged solutions like vSAN deliver fast reliable, and productive results.