Comparison between VMFS3 & VMFS5

Comparison between VMFS3 & VMFS5

VMFS3

VMFS5

  • Single Largest extent of 2TB less 512bytes
  • Uses MSDOS partition table
  • Supports 64TB Spanned Volume (32 extents x 2TB)
  • Different block size based on the datastore size
    (1MB/2MB/4MB/8MB)
  • Max size of RDM in virtual compatibility mode would be 2TB less 512bytes.
  • Max size of RDM in physical compatibility mode would be 2TB less 512bytes.
  • Single largest extent of 64TB
  • Uses GPT partition table
  • Supports 64TB Spanned Volume (32 extents with any size combination)
  • Unified 1MB Block Size
  • Performance improvements in comparison with VMFS3
  • Max size of RDM in virtual compatibility mode would be 2TB less 512bytes.
  • Max size of RDM in physical compatibility mode would be 64TB.
  • You will use VMFS3 if you have a vSphere environment which is mix of vSphere 4.x (also 3.x) & 5.x hosts. Presently VMFS5 datastores cannot be accessible to hosts running an ESXi version less than vSphere 5.0
  • You can upgrade from VMFS3 to VMFS5 but cannot downgrade.
  • On upgrading a VMFS3 datastore, the datastore starts to use GPT partition format only after the datastore has been extended (within the extent) beyond 2TB (less 512bytes). Not sure if the behaviour is similar for a spanned volume as well, but I believe that is how it should behave.
  • Storage vMotion (migration across datastores) between a VMFS3 and VMFS5 volume is supported if you are using a vSphere 5.x host.
  • vMotion (migration across hosts) in vSphere 5.x is supported in either cases when shared storage is VMFS3 or VMFS5.

For additional information refer vSphere 5.0 configuration maximums guide.

I would also suggest to go through the VMFS5 FAQ document which has some great information.

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2 thoughts on “Comparison between VMFS3 & VMFS5

  1. Question – is it supported to do a Storage VMotion on an vSphere 5.x host from a VM living on VMFS5 (created previously on VMFS3) that has not changed to the GPT format back to a VMFS3 filesystem? Would there be anything stopping this from having?

    • Hi Shawn,

      I have never tested this specific use case. But here’s my take:

      Storage vMOtion is storage type independent. So you can migrate from a local VMFS datastore to a shared VMFS datastore or to a NFS datastore and vice-a-versa.

      So I would say migrating from VMFS5 to VMFS3 should work without any issues. Again to note here GPT & MBR is the partition table format **used by VMFS** only. And (I believe) the partition table format type of the VMFS has no implications on the VM or the VMDK.

      However, Wearing my QA engineer’s hat, I would say these are tricky migrations and may have some gotchas around the boundary conditions. Hence try with a couple of VMs first. 🙂

      Hope this answers your question. Thanks.
      Regards / Shekhar

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