vsphere-esxi-vcenter-server-55-storage-guide

Chapter 19 Working with Virtual SANTable 19‐2. Storage Policy Attributes (Continued)CapabilityFlash read cache reservationForce provisioningDescriptionSSD capacity reserved as read cache for the virtual machineobject. Specified as a percentage of the logical size of theobject. Should be used only to address read performanceissues. Reserved flash capacity cannot be used by otherobjects. Unreserved flash is shared fairly among all objects.Default value is 0%. Maximum value is 100%.NOTE By default, Virtual SAN dynamically allocates readcache to storage objects based on demand. This representsthe most flexible and the most optimal use of resources. Asa result, typically, you do not need to change the default 0value for this parameter.To increase the value when solving a performanceproblem, exercise caution. Over-provisioned cachereservation across several virtual machines can cause SSDspace to be wasted on over-reservations and not beingavailable to service the workloads that need the space at agiven time. This might lead to performance degradation.If the option is set to Yes, the object will be provisionedeven if the policy specified in the storage policy is notsatisfiable by the datastore. Use this parameter inbootstrapping scenarios and during an outage whenstandard provisioning is not longer possible.The default No is acceptable for most productionenvironments. Virtual SAN attempts to provision a virtualmachine even when all requirements cannot be met.View Virtual SAN Storage ProvidersVirtual SAN automatically configures and registers a storage provider for each host in the Virtual SANcluster.The Virtual SAN storage providers use VASA to report a set of the datastore capabilities to vCenter Server.They also communicate with the Virtual SAN layer to report the storage requirements of the virtualmachines. For more information about storage providers, see Chapter 26, “Using Storage Providers,” onpage 253.Virtual SAN registers a separate storage provider for each host in the Virtual SAN cluster, using thefollowing URL:http://host_ip:8080/version.xmlwhere host_ip is the actual IP of the host.Verify that the storage providers are registered.Procedure1 Browse to the vCenter Server in the vSphere Web Client navigator.2 Click the Manage tab, and click Storage Providers.The storage providers for Virtual SAN appear on the list.What to do nextIf you delete or unregister the Virtual SAN storage provider for troubleshooting purposes, you can registerit manually. See “Register Storage Providers,” on page 255.VMware, Inc. 189