Shulou(Shulou.com)06/02 Report--

Prepare the storage device

Use flash devices and disks as required by vSAN.

Confirm that the cluster has the capacity to support the expected virtual machine consumption and the primary level of failures allowed in the virtual machine storage policy.

The storage device must meet the following requirements in order to be declared by vSAN:

1. The storage device is local to the ESXi host. VSAN could not declare the remote device.

two。 The storage device does not have any existing partition information.

3. All-flash disk groups and mixed disk groups cannot exist at the same time on the same host.

Raw capacity and available capacity

Raw storage capacity that is larger than the capacity of the virtual machine so that some problems can be handled.

1. Do not include the size of the flash cache device in the capacity. These devices are not available for storage, and unless you have added flash devices for storage, they will be used as caches.

two。 There is enough space to handle the allowable Primary level of failures (PFTT) value in the virtual machine storage policy. If the PFTT is greater than 0, the device footprint will be increased. If PFTT is set to 1, the footprint is doubled. If PFTT is set to 2, the footprint will be tripled, and so on.

3. Verify that the vSAN data store has enough space to operate by checking the space on each host, rather than on the consolidated vSAN data store object. For example, when you withdraw a host, all available space in the data store may be on the host you are withdrawing. The cluster will not be able to accommodate withdrawal to other hosts.

4. "if a workload with thin standby storage starts to consume a lot of storage, provide enough space to prevent insufficient data storage capacity."

5. Verify that physical storage can accommodate the reprotection and maintenance mode of hosts in the vSAN cluster.

6. Note the free storage space overhead of vSAN.

7. Disk format version 1.0 adds additional overhead of approximately 1 GB per capacity device.

8. Disk format version 2.0 adds additional overhead, usually no more than 1-2% capacity per device.

9. Disk format 3.0 and later adds additional overhead, usually no more than 1-2% capacity per device. If deduplication and compression and software checksum are enabled, each device requires an additional overhead of approximately 6.2% capacity.

The influence of vSAN Policy on capacity

The vSAN storage policy of a virtual machine affects capacity devices in a number of ways.

Table 4-1. VSAN virtual machine policy and raw capacity

Aspects of policy impact describe policy changes

1. The allowed primary level of failures (PFTT) affects the physical storage space that you must provide for the virtual machine. The higher the PFTT value, the higher the availability and the more space must be provided.

two。 When PFTT is set to 1, the VMDK file of the virtual machine must have two copies. When PFTT is set to 1, 50 GB VMDK files need 100GB space on different hosts. If you change PFTT to 2, you must have enough space on the hosts in the cluster to support three copies of VMDK or 150 GB space.

3. Some policy changes, such as the number of new disk strips per object, require temporary resources. VSAN recreates the objects affected by the changes. For a certain time, physical storage must accommodate both old and new objects.

"when reprotecting or maintaining free space in mode puts a host in maintenance mode or clones a virtual machine, the data store may not be able to withdraw from the virtual machine object, although the vSAN data store indicates that there is enough free space." This insufficient space occurs if the free space is on the host that will be placed in maintenance mode.

Use ESXCLI to mark flash devices as capacity devices

You can use esxcli to manually mark flash devices on each host as capacity devices.

prerequisite

Make sure you are using vSAN 6.5 or later.

Steps

1. To know the name of the flash device that you want to mark as a capacity device, run the following command on each host.

a. In ESXi Shell, run the esxcli storage core device list command.

b. Locate the device name at the top of the command output and make a note of that name.

The command takes the following options:

Table 4-2. Command option

Option description-d |-- disk=str the name of the device you want to mark as the capacity device. For example, mpx.vmhba1:C0:T4:L0-t |-- tag=str selects the tag to add or remove. For example, the capacityFlash tag is used to mark capacity flash devices.

This command lists all the device information identified by ESXi.

two。 In the output, verify that the Is SSD property of the device is true.

3. To mark a flash device as a capacity device, run the esxcli vsan storage tag add-d-t capacityFlash command.

For example, the esxcli vsan storage tag add-t capacityFlash-d mpx.vmhba1:C0:T4:L0 command, where mpx.vmhba1:C0:T4:L0 is the device name.

4. Verify that the flash device is marked as a capacity device.

a. In the output, determine whether the IsCapacityFlash property of the device is set to 1.

Example: command output

You can run the vdq-Q-d command to verify the IsCapacityFlash properties. For example, run vdq-Q-d

The mpx.vmhba1:C0:T4:L0 command returns the following output

\ {

"Name": "mpx.vmhba1:C0:T4:L0"

"VSANUUID":

"State": "Eligible for use by VSAN"

"ChecksumSupport": "0"

"Reason": "None"

"IsSSD": "1"

"IsCapacityFlash": "1"

"IsPDL": "0"

\}

Use ESXCLI to unmark flash devices used as capacity devices

You can unmark flash devices that are used as capacity devices so that they can be used for caching.

Steps

1. To unmark a flash device that has been marked as capacity, run the esxcli vsan storage tag remove-d-t capacityFlash command. For example, esxcli vsan storage tag remove-t capacityFlash

The-d mpx.vmhba1:C0:T4:L0 command, where mpx.vmhba1:C0:T4:L0 is the device name.

two。 Verify that the flash device is unmarked.

An in the output, determine whether the IsCapacityFlash property of the device is set to 0.

Example: command output

You can run the vdq-Q-d command to verify the IsCapacityFlash properties. For example, run vdq-Q-d

The mpx.vmhba1:C0:T4:L0 command returns the following output.

[

\ {

"Name": "mpx.vmhba1:C0:T4:L0"

"VSANUUID":

"State": "Eligible for use by VSAN"

"ChecksumSupport": "0"

"Reason": "None"

"IsSSD": "1"

"IsCapacityFlash": "0"

"IsPDL": "0"

\}

Use RVC to mark flash devices as capacity devices

Run the vsan.host_claim_disks_differently RVC command to mark the storage device as Flash, capacity Flash, or disk (HDD).

You can use the RVC tool to mark flash devices individually or in batches as capacity devices by specifying the model of the device. If you want to mark a flash device as a capacity device, you can join it in an all-flash disk group.

Note: the vsan.host_claim_disks_differently command does not check the device type before marking the device. This command marks any devices that are attached using the capacity_flash command option, including disks and devices that are already in use. Be sure to verify the status of the device before marking.

For information about RVC commands managed by vSAN, see the RVC Command reference Guide.

prerequisite

a. Make sure you are using vSAN 6.5 or later.

b. Verify that SSH is enabled on the vCenter Server Appliance.

Steps

1. Open the SSH connection to vCenter Server Appliance.

two。 Log in to the device using a local account with administrator privileges.

3. Start RVC by running the following command.

Rvc local_user_name@target_vCenter_Server

For example, to mark a capacity flash device as user root using the same vCenter Server Appliance, run the following command:

Rvc root@localhost

4. Enter the password for the user name.

5. Navigate to the vcenter_server/data_center/computers/cluster/hosts directory in the vSphere infrastructure.

6. Run the vsan.host_claim_disks_differently command with the-- claim-type capacity_flash--modelmodel_name option to mark all flash devices of the same model on all hosts in the cluster as capacity devices.

Vsan.host_claim_disks_differently-claim-type capacity_flash-model model_name *

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