Sunday, July 29, 2012

Hotadd limitation

Other than the 1TB vmdk limit with early version of VDDK (fixed in VDDK 1.1.1), the following are the limit and suggestion of HotAdd (similar info can be found in vendor support documentation).

1)Hot-Add only works on SCSI disks, not IDE disks
2)Disable automount on proxy host
3)For block size mismatch issue, the VMFS containing the Target VM and the VMFS containing the VADP proxy must use the same or larger block size. For example, if you back up virtual disk on a datastore with 4Mb blocks, the proxy (vRanger) must also be on a datastore with 4Mb blocks or above. Its strongly recomended to install proxy on VM which is residing on 8Mb.

Other consideration not only applied to hotadd but also other transport mode.
1) change the workingDir to a datastore with enough block size if there are more than 1 vmdk for a VM and they are on different datastore with different block size.  For ex, if C drive is on datastore with 1 MB block size, and D drive is on a datastore with 2 MB block size.  workingDir should be on datastore with 2 MB block size.  See VM KB: 1012384

P.S. Do not use hotadd if there is dynamic disk in the VM.  It is just a headache.  See VM KB: 2006279

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