{"id":521,"date":"2018-09-01T21:09:15","date_gmt":"2018-09-01T18:09:15","guid":{"rendered":"https:\/\/blog.arcak.net\/?p=509"},"modified":"2018-09-01T22:51:27","modified_gmt":"2018-09-01T19:51:27","slug":"vsan-fault-domain-2","status":"publish","type":"post","link":"https:\/\/blog.arcak.net\/index.php\/2018\/09\/01\/vsan-fault-domain-2\/","title":{"rendered":"VMware vSAN Fault Domain"},"content":{"rendered":"

In this article I will explain the subject of vSAN Fault Domains<\/strong>. You can review the original source here<\/strong><\/a>.<\/p>\n

Fault Domains<\/strong>\u00a0allow systems to run in cases where multiple server failures or a cabinet is not reachable by spreading the vSAN<\/strong> cluster across multiple cabinets or blade chassis. One or more servers can be added to each Fault Domain.<\/p>\n

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The Primary level of failures to tolerate (PFTT) <\/strong>policy in vSan<\/strong> cluster depends on the number of failure that the virtual machine can tolerate. When PFTT<\/strong> = 1<\/strong> is defined, any single failure can be recovered\u00a0in vSan Fault Domain<\/strong> (e.g. entire cabinet failure)<\/strong>.<\/p>\n

When a virtual server is provisioned after\u00a0fault domains are configured,<\/strong> the protection objects such as vSAN<\/strong>, replica, and witness\u00a0<\/strong>are\u00a0stored in different fault domains. If the storage-based policy is PFTT<\/strong> = N<\/strong>, vSAN<\/strong>\u00a0requires at least 2n + 1\u00a0<\/strong>number of Fault Domains<\/strong>. If the virtual machines in the vSAN<\/strong> cluster use the Fault Domain<\/strong> policy, the corresponding virtual machine objects are kept in different cabinets.<\/p>\n

In the same way as the vSphere cluster with three nodes, <\/strong>it needs min. 3 units (2 * 1 + 1) Fault Domain <\/strong>in order to provide PFTT = 1<\/strong>.<\/p>\n

If a cabinet is not fully accessible then a high percentage of hardware resources are lost thus it is recommended to create small Fault Domains<\/strong> to minimize the impact.<\/p>\n

The following Best Practises should be followed while working with Fault domains<\/strong>;<\/p>\n