Epson MR Series Technical Reference Manual page 275

MR Series Technical Reference Manual
10. To remove the second 2.5"HDD remove the four screws shown in the figure below securing
the HDD and remove the SHORTPLUG for the 2.5"HDD.
2.5"HDD
SHORT PLUG
When you install two 2.5"HDD, the master or slave can be installed on the top or bottom.
When you install the 2.5"HDD, you need to set the HDD jumpers properly.
When connecting two 2.5"HDDs, one is Master and the other is Slave.
Set Master/Slave by the jumper of the HDD.
As for the procedure, see "HDD".
Example: For the Hitach Travelstar
Slave
Master
To install, reverse the removal procedure.
Rev. I Disassembly and Assembly 9-59