So if your environment is utilizing physical RDMs then you do not need to worry about this setting. It is not for use with physical RDMs (pRDM) as they are not "VMFS backed". The first important thing to note here is that this option is meant for VMDKs or virtual RDMs (vRDM) only. This is a good mindset to have as protecting data should always be the number one goal. There is a fear that if left unspecified (which defaults to "No Sharing") corruption of come kind can happen on the disk. Since RDMs are most often used for situations like clustering this becomes a concern on whether or not this value should be set. When utilizing RDMs people often have questions regarding the "Sharing" option while adding the RDM to the virtual machine (illustrated below). The setting to ignore the inquiry cache may need to be set for RDMs that are leveraging ActiveCluster. In particular, when leveraging ActiveCluster for planned migration of RDMs between arrays, because the device states will be changing in a short amount of time and the guest OS or application may encounter stale data from the host cache. This setting may need to be set depending on the Guest OS or application needs when using RDMs with ActiveCluster or ActiveDR. VMware has observed that some guest operating systems (the Virtual Machine's Operating System) and/or applications require current SCSI INQUIRY data to operate without disruption to the guest or application. By default, the guest OS will get the SCSI INQUIRY data from the ESXi host for RDMs rather than the array directly. VMware has a section in their product documentation that covers how an RDM device can be set so the guest OS will ignore the ESXi host's cache and for the guest to query the array directly for this information. This can be found in this VMware KB. Volume 4 E RDM-Example NTFS Partition 499 GB Healthy Volume # Ltr Label Fs Type Size Status Info
Esxi virtual disk map windows#
All of the multipathing logic is handled in the lower levels of the ESXi host.īelow is an example of what a pRDM looks like within a Windows VM:ĭisk ID: All of the available paths are abstracted from the VM and the RDM is presented as a disk with a single path. This means that no MPIO configuration is required (or needed) within the virtual machines utilizing RDMs. This means that the VMware Native Multipathing Plugin (NMP) is responsible for RDM path management and not the virtual machine. Luckily things are not that complicated and the configuration is no different than that of a VMFS datastore. Now that we know the identifier and LUN ID we can look at the FlashArray to determine which volume is backing the RDMĪs seen above we are able to confirm that this particular RDM is backed by the volume called "space-reclamation-test" on the FlashArray.Ī common question when using Raw Device Maps (RDMs) is where the multipathing configuration should be completed. Because an RDM provides the ability for a virtual machine to access the underlying storage directly it is often thought that configuration within the VM itself was required.
Esxi virtual disk map serial number#
The above string can be analyzed as follows:
Once you have the vml identifier we can then find the LUN ID and the volume identifier to match it to a FlashArray volume. Under the disk properties locate the "Physical LUN" section and note the vml identifier.Ĥ.
Locate the desired RDM you wish to inspect and expand the properties of the disk.ģ. Right click on the virtual machine and select "Edit Settings".Ģ. There are times where you will need to determine which volume on the FlashArray is associated with a Raw Device Mapping.ġ. Identifying the underlying volume for a Raw Device Mapping
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