What effect will this upgrade have on the maximum file size supported by the datastore?

A 2TB VMFS3 datastore has been upgraded to VMFS5. The original block size was 2MB.
What effect will this upgrade have on the maximum file size supported by the datastore?

A.
The maximum virtual disk size remains 512GB

B.
The maximum virtual disk size increases to 1TB

C.
The maximum virtual disk size increases to 32TB providing the datastore is also increased

D.
The maximum virtual disk size increases to 2TB minus 512B

Explanation:
If you have a .vmdk file in VMFS-3 format, with one of this size (depending on block size), then you have:
1MB file block size – max file size is 256GB2MB file block size – max file size is 512GB4MB file block size – max file size is 1TB8MB file block size – max file size is 2TB People think that because we maintain this original file block size in the upgraded VMFS-5, this still has relevance to the maximum size of the VMDK. But this is not true. If you update VMFS-3 to VMFS-5, independently the block size that this VMDK file have in VMFS- 3, now in VMFS-5 format this file can grown up to 2 TB minus 512 bytes, no more than this size. Reference: http://blogs.vmware.com/vsphere/2011/08/2tb-vmdks-on-upgraded-vmfs-3-to-vmfs-5- really.html

3 Comments on “What effect will this upgrade have on the maximum file size supported by the datastore?

  1. Mohsin Alvi says:

    agreed @Ajay
    If you originally had a 1TB VMFS-3 datastore with a block size of 2MB and you upgrade the datastore to VMFS-5…the maximum size VMDK file will still be 512GB (which is the limit of a VMFS-3 2MB block size).

    If you want to create files larger then 512GB then you need to migrate the virtual machines off the existing datastore, delete the VMFS volume and recreate it as a new VMFS-5 datastore.

    So Ans is A

  2. ramzi says:

    @ajay,

    the answer would still be D, as mentioned in your kb article:

    “When upgrading a VMFS datastore from VMFS-3 to VMFS-5, you can extend a datastore past 2 TB – 512 B. The caveat to upgrading a VMFS-3 datastore to VMFS-5 is that it will inherit the block size properties of the original VMFS-3 datastore.

    If you upgrade to VMFS-5 from VMFS-3 then regardless of the block size, VMFS-5 uses double-indirect addressing to cater for large files (up to a size of 2 TB – 512 B) on upgraded VMFS-3 volumes. For example, if the VMDK goes beyond 512 GB it will switch to using double-indirect addressing, which will allow for VMDKs up to 2 TB – 512 B.”


Leave a Reply

Your email address will not be published. Required fields are marked *