All Flash vSAN – How to tag an SSD disk as storage tier

Traditional vSAN is the combination of cache component based on flash storage and capacity layer based usually on traditional magnetic disks. Since v6.0, vSAN supports All Flash storage. In other words, both the caching and the storage layer can be made up from flash based storage, like SSD is. Here I will cover how to use the command line to perform device tagging. For GUI version, please refer to the article in the section Related Posts on the bottom of this page.

First let’s see how is your storage tagged in ESXi. Connect to your ESXi host via SSH and run the following command to identify your storage devices:

# esxcli storage core devices list

This will give output as this:

   Display Name: Local ATA Disk (t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__)
   Has Settable Display Name: true
   Size: 381554
   Device Type: Direct-Access
   Multipath Plugin: NMP
   Devfs Path: /vmfs/devices/disks/t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__
   Vendor: ATA
   Model: INTEL SSDSC2BA40
   Revision: 5DV1
   SCSI Level: 5
   Is Pseudo: false
   Status: on
   Is RDM Capable: false
   Is Local: true
   Is Removable: false
   Is SSD: true
   Is VVOL PE: false
   Is Offline: false
   Is Perennially Reserved: false
   Queue Full Sample Size: 0
   Queue Full Threshold: 0
   Thin Provisioning Status: yes
   Attached Filters:
   VAAI Status: unsupported
   Other UIDs: vml.010000000042545456343438343031305034303048474e2020494e54454c20
   Is Shared Clusterwide: false
   Is Local SAS Device: false
   Is SAS: false
   Is USB: false
   Is Boot USB Device: false
   Is Boot Device: false
   Device Max Queue Depth: 31
   No of outstanding IOs with competing worlds: 32
   Drive Type: unknown
   RAID Level: unknown
   Number of Physical Drives: unknown
   Protection Enabled: false
   PI Activated: false
   PI Type: 0
   PI Protection Mask: NO PROTECTION
   Supported Guard Types: NO GUARD SUPPORT
   DIX Enabled: false
   Emulated DIX/DIF Enabled: false

Now we run the following command to check if this device is tagged as capacity tier:

vdq -qH -d  t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__

and the output clearly shows that the device is NOT tagged as capacity tier:

         Name:  t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__
         VSANUUID:  521505d8-a11e-01d5-15e4-7316a478cdf1
         State:  In-use for VSAN
         Reason:  None
         IsSSD?:  0
         IsCapacityFlash?:  0
         IsPDL?:  0

To tag this device as capacity tier run the following command:

esxcli vsan storage tag add -d  t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__ -t capacityFlash

Now after running the vdq command again, we can see that device is tagged as capacity layer:

         Name:  t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__
         VSANUUID:  521505d8-a11e-01d5-15e4-7316a478cdf1
         State:  In-use for VSAN
         Reason:  None
         IsSSD?:  0
         IsCapacityFlash?:  1
         IsPDL?:  0

Now you can proceed with creating the vsan configuration.

If you receive the following error:

Unable to add tag to disk: Disk t10.ATA_____INTEL_SSDSC2BA400G3_____________________BTTV4484010P400HGN__ has partitions. Disk with partitions not eligible for tagging operation.

Remove all existing paritions using vSphere Web Client of your VMware vCenter.

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