Cisco NSS324 Quick Start Manual page 9

There is also a HDD sequence label included in the package
contents that can be placed on the top of the chassis, showing the
disk drive sequence. For example, 1-4 for the NSS324 and 1-6 for
the NSS326.
HDD Sequence
1 2 3 4 5 6
Cisco Small Business NSS324 and NSS326 Smart Storage 9