Hi Balaji,  You cannot mix X-Bricks of different sizes in the same XtremIO cluster. Please reach out to an All Flash SE for your region to understand the reasons and decide on the next steps for your customer.
Hi, My customer is adding a new X-Brick (1X-20TB) to existing 1X-40TB. To complete the task, should we perform OCE? Can someone share documents related to this?  Thanks in advance!
XtremIO - adding more Xbricks