VSAN-Troubleshooting-Reference-Manual

Diagnostics and Troubleshooting Reference Manual – Virtual SAN
New disk is placed in the ESXi host
Expected behaviors:
When a new partition-free disk is placed on the ESXi host, whether or not the
ESXi host detects it automatically is dependent on whether the storage
controller is configured for RAID-0 or pass-through. If pass-through, the
device should be visible on a rescan. If a RAID-0 configuration is required, a
RAID-0 volume will need to be configured on the device for it to be visible to
the host. The Virtual SAN Administrators Guide will have further details on
the steps involved.
If the cluster is in automatic mode, Virtual SAN will claim the disk and add it
to any of the existing disk groups.
If the cluster is in manual mode, an administrator will have to manually claim
the disk by adding it to a disk group via the vSphere web client UI.
If the device is a flash device, and the wish is to use it as part of the capacity
layer in an all-flash configuration, additional steps are needed to mark it as a
capacity device. The Virtual SAN Administrators Guide will have further
details on the steps involved.
New cache tier SSD is placed in the ESXi host
Expected behaviors:
When replacing a cache tier flash device with a new cache tier flash device,
whether or not the ESXi host detects it automatically is dependent on
whether the storage controller is configured for RAID-0 or pass-through. If
pass-through, the device should be visible on a rescan. If a RAID-0
configuration is required, a RAID-0 volume will need to be configured on the
SSD for it to be visible to the host. The Virtual SAN Administrators Guide
should have further details.
Next, an administrator must manually decommission existing magnetic disks
(hybrid) or SSDs (all-flash) in the capacity tier by removing the disks from
their current disk group. Unless you do this, these disks cannot be associated
to the new cache tier SSD. Note that this decommissioning process does not
preserve the data on the disks. The data will be rebuilt automatically once
the new disk group is created.
If you are doing a proactive replacement of a cache tier SSD, you can use
maintenance mode to do a full evacuation of the data from the disk group
before replacing the SSD. In fact, Virtual SAN 6.0 allows for the evacuation of
data from individual capacity devices when they are being removed from a
disk group. However this is obviously not possible on a failure.
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