Symptom:

You are trying to configure Host Cache Configuration feature in VMware vSphere. The Host Cache feature will swap memory to a local SSD drive, if vSphere encounters memory constraints. It is similar to the famous Windows ReadyBoost.

Host Cache requires an SSD drive, and ESXi will detect the drive type as SSD. If the drive type is NOT SSD, Host Cache Configuration will not be allowed.

However, even though you put in some local SSD drives on the ESXi host, and also have an SSD drive on your storage array coming through, ESXi refuses to recognize the drives as SSD type, and thus refuses to let you use Host Cache.

Solution:

Apply some CLI commands to force ESXi into understanding that your drive is really SSD. Then reconfigure your Host Cache.

Instructions:

Look up the name of the disk and its naa.xxxxxx number in VMware GUI. In our example, we found that the disks that are not properly showing as SSD are:

• Dell Serial Attached SCSI Disk (naa.600508e0000000002edc6d0e4e3bae0e)  — local SSD
• DGC Fibre Channel Disk (naa.60060160a89128005a6304b3d121e111) — SAN-attached SSD

Check in the GUI that both show up as non-SSD type.

SSH to ESXi host. Each ESXi host will require you to look up the unique disk names and perform the commands below separately, once per host.

Type the following commands, and find the NAA numbers of your disks.

In the examples below, the relevant information is highlighted in RED.

The commands you need to type are BOLD.

The comments on commands are in GREEN.

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~ # esxcli storage nmp device list

naa.600508e0000000002edc6d0e4e3bae0e

Device Display Name: Dell Serial Attached SCSI Disk (naa.600508e0000000002edc6d0e4e3bae0e)

Storage Array Type: VMW_SATP_LOCAL

Storage Array Type Device Config: SATP VMW_SATP_LOCAL does not support device configuration.

Path Selection Policy: VMW_PSP_FIXED

Path Selection Policy Device Config: {preferred=vmhba0:C1:T0:L0;current=vmhba0:C1:T0:L0}

Path Selection Policy Device Custom Config:

Working Paths: vmhba0:C1:T0:L0

naa.60060160a89128005a6304b3d121e111

Device Display Name: DGC Fibre Channel Disk (naa.60060160a89128005a6304b3d121e111)

Storage Array Type: VMW_SATP_ALUA_CX

Storage Array Type Device Config: {navireg=on, ipfilter=on}{implicit_support=on;explicit_support=on; explicit_allow=on;alua_followover=on;{TPG_id=1,TPG_state=ANO}{TPG_id=2,TPG_state=AO}}

Path Selection Policy: VMW_PSP_RR

Path Selection Policy Device Config: {policy=rr,iops=1000,bytes=10485760,useANO=0;lastPathIndex=1: NumIOsPending=0,numBytesPending=0}

Path Selection Policy Device Custom Config:

Working Paths: vmhba2:C0:T1:L0

naa.60060160a891280066fa0275d221e111

Device Display Name: DGC Fibre Channel Disk (naa.60060160a891280066fa0275d221e111)

Storage Array Type: VMW_SATP_ALUA_CX

Storage Array Type Device Config: {navireg=on, ipfilter=on}{implicit_support=on;explicit_support=on; explicit_allow=on;alua_followover=on;{TPG_id=1,TPG_state=ANO}{TPG_id=2,TPG_state=AO}}

Path Selection Policy: VMW_PSP_RR

Path Selection Policy Device Config: {policy=rr,iops=1000,bytes=10485760,useANO=0;lastPathIndex=1: NumIOsPending=0,numBytesPending=0}

Path Selection Policy Device Custom Config:

Working Paths: vmhba2:C0:T1:L3

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Note that the Storage Array Type is VMW_SATP_LOCAL for the local SSD drive and VMW_SATP_ALUA_CX for the SAN-attached SSD drive.

Now we will check to see if in CLI, ESXi reports the disks as SSD or non-SSD for both disks. Make sure to specify your own NAA number when typing the command.

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~ # esxcli storage core device list –device=naa.600508e0000000002edc6d0e4e3bae0e

naa.600508e0000000002edc6d0e4e3bae0e

Display Name: Dell Serial Attached SCSI Disk (naa.600508e0000000002edc6d0e4e3bae0e)

Has Settable Display Name: true

Size: 94848

Device Type: Direct-Access

Multipath Plugin: NMP

Devfs Path: /vmfs/devices/disks/naa.600508e0000000002edc6d0e4e3bae0e

Vendor: Dell

Model: Virtual Disk

Revision: 1028

SCSI Level: 6

Is Pseudo: false

Status: degraded

Is RDM Capable: true

Is Local: false

Is Removable: false

Is SSD: false

Is Offline: false

Is Perennially Reserved: false

Thin Provisioning Status: unknown

Attached Filters:

VAAI Status: unknown

Other UIDs: vml.0200000000600508e0000000002edc6d0e4e3bae0e566972747561

~ # esxcli storage core device list –device=naa.60060160a89128005a6304b3d121e111

naa.60060160a89128005a6304b3d121e111

Display Name: DGC Fibre Channel Disk (naa.60060160a89128005a6304b3d121e111)

Has Settable Display Name: true

Size: 435200

Device Type: Direct-Access

Multipath Plugin: NMP

Devfs Path: /vmfs/devices/disks/naa.60060160a89128005a6304b3d121e111

Vendor: DGC

Model: VRAID

Revision: 0430

SCSI Level: 4

Is Pseudo: false

Status: on

Is RDM Capable: true

Is Local: false

Is Removable: false

Is SSD: false

Is Offline: false

Is Perennially Reserved: false

Thin Provisioning Status: yes

Attached Filters: VAAI_FILTER

VAAI Status: supported

Other UIDs: vml.020000000060060160a89128005a6304b3d121e111565241494420

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Now we will add a rule to enable SSD on those 2 disks. Make sure to specify your own NAA number when typing the commands.

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~ # esxcli storage nmp satp rule add –satp VMW_SATP_LOCAL –device naa.600508e0000000002edc6d0e4e3bae0e –option=enable_ssd

~ # esxcli storage nmp satp rule add –satp VMW_SATP_ALUA_CX –device naa.60060160a89128005a6304b3d121e111 –option=enable_ssd

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Next, we will check to see that the commands took effect for the 2 disks.

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~ # esxcli storage nmp satp rule list | grep enable_ssd

VMW_SATP_ALUA_CX     naa.60060160a89128005a6304b3d121e111                                                enable_ssd                  user

VMW_SATP_LOCAL       naa.600508e0000000002edc6d0e4e3bae0e                                                enable_ssd                  user

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Then, we will run storage reclaim commands on those 2 disks. Make sure to specify your own NAA number when typing the commands.

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~ # esxcli storage core claiming reclaim -d naa.60060160a89128005a6304b3d121e111

~ # esxcli storage core claiming reclaim -d naa.600508e0000000002edc6d0e4e3bae0e

Unable to unclaim path vmhba0:C1:T0:L0 on device naa.600508e0000000002edc6d0e4e3bae0e. Some paths may be left in an unclaimed state. You will need to claim them manually using the appropriate commands or wait for periodic path claiming to reclaim them automatically.

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If you get the error message above, that’s OK. It takes time for the reclaim command to work.

You can check in the CLI by running the command below and looking for “Is SSD: false”

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~ # esxcli storage core device list –device=naa.600508e0000000002edc6d0e4e3bae0e

naa.600508e0000000002edc6d0e4e3bae0e

Display Name: Dell Serial Attached SCSI Disk (naa.600508e0000000002edc6d0e4e3bae0e)

Has Settable Display Name: true

Size: 94848

Device Type: Direct-Access

Multipath Plugin: NMP

Devfs Path: /vmfs/devices/disks/naa.600508e0000000002edc6d0e4e3bae0e

Vendor: Dell

Model: Virtual Disk

Revision: 1028

SCSI Level: 6

Is Pseudo: false

Status: degraded

Is RDM Capable: true

Is Local: false

Is Removable: false

Is SSD: false

Is Offline: false

Is Perennially Reserved: false

Thin Provisioning Status: unknown

Attached Filters:

VAAI Status: unknown

Other UIDs: vml.0200000000600508e0000000002edc6d0e4e3bae0e566972747561

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Check in the vSphere Client GUI. Rescan storage.

If it still does NOT say SSD, reboot the ESXi host. 

Then look in the GUI and rerun the command below.

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~ # esxcli storage core device list —device=naa.60060160a89128005a6304b3d121e111

naa.60060160a89128005a6304b3d121e111

Display Name: DGC Fibre Channel Disk (naa.60060160a89128005a6304b3d121e111)

Has Settable Display Name: true

Size: 435200

Device Type: Direct-Access

Multipath Plugin: NMP

Devfs Path: /vmfs/devices/disks/naa.60060160a89128005a6304b3d121e111

Vendor: DGC

Model: VRAID

Revision: 0430

SCSI Level: 4

Is Pseudo: false

Status: on

Is RDM Capable: true

Is Local: false

Is Removable: false

Is SSD: true

Is Offline: false

Is Perennially Reserved: false

Thin Provisioning Status: yes

Attached Filters: VAAI_FILTER

VAAI Status: supported

Other UIDs: vml.020000000060060160a89128005a6304b3d121e111565241494420

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If it still does NOT say SSD, you need to wait. Eventually, the command works and displays as SSD in CLI and the GUI. 

More Information:

See the article below: