HPE ProLiant DL345 Gen11 Service And Maintenance Manual page 276

Rear: 2 SFF drive bay numbering Rear: 2 SFF drive bay numbering
E3.S drive bay numbering E3.S drive bay numbering
E3.S drive box uses the 12 E3.S 32G x4 NVMe UBM5 EC drive backplane.
For more information on the drive backplane description, see Drive backplane naming.
Drive backplane naming Drive backplane naming
HPE ProLiant DL345 Gen11 Server Service and Maintenance Guide 276