[Lustre-discuss] ldiskfs-ext4 interoperability question

[Nirmal Seenu]

Our current Lustre servers run the version 1.8.1.1 with the regular ldiskfs.

We are looking to expand our Lustre file system with new servers/storage and upgrade to all the lustre servers to 1.8.4 as well at the same time. We 
would like to make use of the ldiskfs-ext4 on the new servers to use larger OSTs.

I just want to confirm the following facts:

1. Is is possible to run different versions of ldiskfs on different OSSs of the same lustre file system.

2. Can I install the Lustre RPMs meant for the ext4 system on our older servers that were formatted with the older ldiskfs and expect it to work? Do I 
have to do any ext3-ext4 conversion or equivalent to make this work?

TIA
Nirmal