VMFS does not stripe across LUNs or extents

Note that the VMFS does not stripe across LUNs when more
than one LUN is allocated to a given VMFS volume.

VMFS Best Practices Guide

The hosts try to put distance between themselves on the datastore to reduce any contention for resources, but they still try to keep the objects that they manage close together.

VMFS Extents – Are they bad, or simply misunderstood?


ESXi partedUtil for when trouble strikes

A VMware admin would never have to worry about using partedUtil to manipulate partition table on the CLI until trouble strikes.Starting VMFS5 (ESX 5.x and above), VMware switched to GUID Partition Table (gpt) from MBR partition(labeled msdos) to support bigger disk, larger than 2TB. fdisk does not support gpt partition and hence partedUtil.

partedUtil without any arguments will display the options available and syntax.
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Dude, where’s my VMFS datastore?

Consider these situations. Suddenly, a VM goes down and the datastore on which it sits is greyed out in vCenter. A virtual machine is unable access one of it’s disks. You are unable to browse the datastore because it is greyed out. The VMFS datastore is inaccessible across hosts in the cluster.

What can we do? The first thing we need to check is, can the host access the VMFS datastore? Most likely not because we can’t browser it from vSphere client GUI. To be certain, we can check it from the command line. ssh to the ESXi host and run one of these commands Continue reading