IBM Support

Unable to add a new disk to a Volume Group due to mismatch in disk block size.



When a customer tries to add a new disk to a Volume Group, he gets the error message below: #extendvg rootvg hdisk2 0516-1980 extendvg: Block size of all disks in the volume group must be the same. Cannot mix disks with different block sizes. 0516-792 extendvg: Unable to extend volume group.


Such an error means you cannot mix a physical volume (PV) of 4 KB block size with PV blocks of other sizes. The block size of all PVs in the volume group must be the same.

This is explicitly mentioned in the man page below for the extendvg command:

Resolving The Problem

Unfortunately, there is no way to fix that issue. because AIX, at the present, only supports 4K block sizes on sissas drives. AIX does not support 4K block sizes on fibre-attached storage. There is no option for block-size translation for SAS disks in firmware nor in AIX kernel.

Naturally, that means that you will not be able to include both sissas drive and fibre-attached drives within the same volume group, since the volume group requires all disks within the volume group to utilize the same disk block size.

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Document Information

Modified date:
17 June 2018