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spectVM
Enthusiast
Enthusiast

Is TRIM supported with Raw Device Mapping (RDM)?

As per the title.

I am looking to RDM some SSD that need TRIM. Will TRIM work through RDM?

Thanks.

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beckham007fifa

Is that Trim available on Enterprise storage? I guess it is there in the conventional model from the time SSD became cheap for daily purpose.

Once you have your RDM created, it is all the Vsphere and VMs to use it. You have VC and host to control RDM LUN's, why would you need to use TRIM to delete anything internally?

Regards, ABFS
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spectVM
Enthusiast
Enthusiast

Thanks for the reply. I am referring more about mapping a locale SATA SSD as RDM.

I have done this before with regular hard drives with full SMART support and the likes. So, now K wonder whether a TRIM command would be supported.

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beckham007fifa

In order to work correctly, TRIM has to be supported by both the solid-state drive and the operating system you are using. It will be highly depended on what type of OS you are using. I couldn't find any evidence of VMware Supporting it with RDM. But I think physical RDM should be supported but not sure about virtual RDMs. However, RDM is basically supported with the complete LUN, partitions etc is not supported. That SSD should be a complete LUN for it to work.

Cheers Smiley Happy

Regards, ABFS
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beckham007fifa

In order to work correctly, TRIM has to be supported by both the solid-state drive and the operating system you are using. It will be highly depended on what type of OS you are using. I couldn't find any evidence of VMware Supporting it with RDM. But I think physical RDM should be supported but not sure about virtual RDMs. However, RDM is basically supported with the complete LUN, partitions etc is not supported. That SSD should be a complete LUN for it to work.

Cheers Smiley Happy

Regards, ABFS
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spectVM
Enthusiast
Enthusiast

The OS will be Windows 8.1.

I am also talking of physical RDM and not LUN RDM.

Essentially, my test box does not have passthrough. However, I wish to give the VM the full SSD through RDM with the hope of having TRIM supported.

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spectVM
Enthusiast
Enthusiast

I have the same question.

I have setup a VM with a physical RDM to an SSD. The physical RDM was created through the vSphere client as it sees the disk as supported for RDM.

The OS is Windows 8.1. Windows says trim is enabled, which is bogus. It says the same for a W2k12R2 install with a VMDK disk.

I tried TrimCheck, which says trim is not enabled.

The disk is described as "ATA Samsung SSD 840 SCSI Disk Device".

What gives?

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