You will need the adapter number to determine the serial number of the enclosures attached.
Running lsi-show will show the Enclosure Information with the Id. This is known as the Adapter number when running megacli. Then running megacli will show the serial number for the Adapter.
For example, running lsi-show, the Adapter number is a2 in this case:
Controller Information
Id Serial No Firmware Encl LD PD Product Name
a2 24P005M 3.131.05-3415 1 1 12 PERC H810 Adapter
Enclosure Information
Id Drives
25 22 21 13 16 15 14 19 18 17 20 23 24
Running megacli -encinfo -a2 | grep Vendor will show that DELL is the vendor name and the serial number of the attached enclosures.
In the example below, the serial number is HSH5T2.
megacli -encinfo -a2| grep Vendor
Vendor Identification : DELL
Vendor Specific : HSH5T2
Remember, when requesting a drive replacement for a failed drive, include the line from the lsi-show output indicating the failed drive, the enclosure serial number, along with the shipping address, contact name and phone number.