So, I've found the error in this setup, and the reason why my device wasn't accepting the SSD originally:
The SSD must NOT be initialized.
There is NO need to copy ANYTHING to the SSD, just make certain it has nothing marked active/bootable/etc.
As a Windows users, this would require an administrative command prompt:
"diskpart", "list disk",
-then # based on which is the target drive: "select disk #", "clean", (optional "create partition primary"), "exit"
Do NOT allow system to initialize disk.
Install this blank, uninitialized disk into the powered-down SRX.
Keep in mind: the first boot with the new SSD drive will be an extra 15+ minutes for the SRX to format your drive, more time for larger drive.
This has been working flawlessly for us the past eight days. Really nice to have log streams handy.
Added this to our configuration: (in the beginning of the "security { " section)
log {
mode stream;
report;
}
Ignore my earlier section about "copy USB device image to SSD." instead, simply wipe the SSD drive clean as described above.
a disk utility which could "secure erase" the drive may also work.
End result must have a blank drive, so the SRX can format it for logging.
-You won't have to set the USB as your boot device, either.
Just make certain you have an appropriate JUNOS version installed (110), then shut down to install the SSD.
After it comes back up, add stream mode and report to security log configuration.