backups failing on new vmfs 5 due to 1mb limitation

[dlee2654]

Hello, we have a situation where we have a few large VMs that were failing to backup using the vRanger product.  at the time, we were on ESXi 4.1 and we had to create a new volume with a 4mb block size or the file would not back up.  Now we have upgraded to version 5.0 and purchased a new storage array.  the new VMFS volumes are version 5 and now we are getting the exact same error as before.  I dont know all the particulars but my backup administrator insists its because the block size is only 1mb on the volume.  I cannot find any way to create a new VMFS 5 volume with larger than 1MB.  Has anyone else run into this issue?

[a_p_]

With the unified 1MB block size for VMFS5, your virtual disks can have a maximum size of ~2,032 GB in order to be able to create snapshots. Basically the maximum virtual disk size is 2TB minus 512 Bytes, but the snapshot .vmdk files contains some additional metadata (up to ~16GB) and therefore the reduced maximum.

André

[dlee2654]

I dont know it seems like the backup software just sees that there is a 1mb block size and compares it to the size of the VM and decides it cannot perform the backup.  I'm not sure about this but I cant think of any other explanation at this time.  we are using PHD for our vm backups.

thanks,

[a_p_]

I don't use PHD myself, but I'm pretty sure they support VMFS5. Which version do you use?

André

[sarad]

Are you positive that this storage array was created as new VMFS5 and not upgraded from VMFS 3?  The upgrade could carry over the same issues with block size incompatibility.

[dlee2654]

when I look at the datastore details it says under "Formatting" File system: VMFS 5.54, Block Size: 1MB

forgot to add that I created this VMFS datastore myself very recently just for the purpose of remedying the situation but it did not work.

[dlee2654]

our backup administrator stated that he discussed with PHD support and they disabled "CBT" and this allowed the backups to run successfully.  He no longer wants to pursue the issue and considers it solved.  thanks for all the replies much appreciated.