Issue: unable to add disks to the disk group.
HPE MSA 1040/2040/2042 Best practices
https://h20195.www2.hpe.com/v2/Getdocument.aspx?docname=4AA4-6892ENW
Please check page number 39 and 40. You will see following:
Page number 39
Note Disk Group Expansion is not supported with Virtual Storage. If you have Virtual Storage and are running out of storage space, the procedure to get more storage space would be to add another Disk Group to a pool.
Page number 40:
Note Disk Group Expansion is only available when using Linear Storage. During Disk Group expansion, other disk utilities are disabled. These utilities include Disk Group Scrub and Rebuild
Hope this helps