snapshot media : no supported on SRX1500
root@SRXbuffalo> request system software add /var/tmp/junos-srxsme-18.3R1.9.tgz
NOTICE: Validating configuration against junos-srxsme-18.3R1.9.tgz.
NOTICE: Use the 'no-validate' option to skip this if desired.
Formatting alternate root (/dev/da0s2a)...
newfs: /dev/da0s2a: failed to open disk for writing
ERROR: Could not format alternate root
...