Degraded Device Handling (DDH) or Dying Disk Handling as it was formerly known, is a feature that has been available in vSAN for some time. However, I regularly get questions about how it works. The DDH behavior has changed significantly over various versions. We may as well begin this post with an overview about the purpose of DDH and then get into the different sort of behaviors. First of all, the reason behind a feature such as DDH is to help avoid cluster performance degradation due to an unhealthy drive. In the early days of vSAN, we had come across…
In this post, I want to talk about a feature called Problematic Disk Handling. Some history behind why we have such a feature can be found in this post. In VSAN 6.2/vSphere 6.0 U2, Problematic Disk Handling has been improved so that it will unmount a problematic disk/diskgroup for two reasons:
The more observant of you may have observed the following entry in the VSAN 6.1 Release Notes: Virtual SAN monitors solid state drive and magnetic disk drive health and proactively isolates unhealthy devices by unmounting them. It detects gradual failure of a Virtual SAN disk and isolates the device before congestion builds up within the affected host and the entire Virtual SAN cluster. An alarm is generated from each host whenever an unhealthy device is detected and an event is generated if an unhealthy device is automatically unmounted. The purpose of this post is to provide you with a little…