How do you locate a failed drive?

Home hobby user here I made a drive spread sheet when I set up the pool, its been very handy already, the drive trays are labeled 1-8 the spread sheet ties the drive tray # to the serial number and wwn.

After first setting up I noticed some of the locations ran hotter than the others. the temperature and serial number are handily right there together in the smart data, the sheet translates this to a drive tray. turns out due to differences in the size of the air holes in the back plane so I re-arranged the 8 drives on a 24 slot backplane for best airflow,

Had I tied the spreadsheet to a chassis location moving things around would require editing the sheet, a step that could be missed (human factors) so that may be a plus for marking the trays.

Marking the serial number on the face of the tray might be handiest of all, no sheet required.