Hardware Overview (M Series, MX Series, T Series, and TX Matrix Routers)
Except for MX80 routers, the Junos OS is installed on both the CompactFlash card and the hard drive. When installed, the internal CompactFlash card is the primary boot device and the hard drive is the secondary boot device. When the internal CompactFlash card is not installed, the hard drive is the primary boot device. Figure 1 shows the standard layout of a typical Routing Engine. On MX80 routers, the internal NAND flash devices (first da0, then da1) act as the primary and secondary boot devices.
Figure 1: Routing Engines
The M Series, MX Series, T Series, TX Matrix, and TX Matrix Plus routers include the following:
System Memory
Starting with Junos OS Release 9.0, all routing platforms require a minimum of 512 MB of system memory on each Routing Engine. All M7i and M10i routers delivered before December 7, 2007, had 256 MB of memory. These routers require a system memory upgrade before you install Junos OS Release 9.0. To determine the amount of memory currently installed on your system, use the show chassis routing-engine command in the command-line interface (CLI).
For more information about upgrading your M7i or M10i router, see the Customer Support Center JTAC Technical Bulletin PSN-2007-10-001: https://www.juniper.net/alerts/viewalert.jsp?txtAlertNumber=PSN-2007-10-001&actionBtn=Search.
Storage Media
Except for MX80 routers, the M Series, MX Series, T Series, TX Matrix, and TX Matrix Plus routers use the following media storage devices:
- CompactFlash card—The CompactFlash card is typically the primary storage device. M7i and M10i routers are not usually delivered from the factory with the CompactFlash card installed. In this case, the hard drive is the primary and only boot device. The M7i and M10i routers can be upgraded to include the CompactFlash card.
- Hard drive or solid state drive—The hard drive is normally the secondary boot device for M Series, MX Series, T Series, and TX Matrix routers. The TX Matrix Plus router includes either a hard drive or a solid state drive as the secondary boot device. When the CompactFlash card is not installed on the router, the hard drive or the solid state drive becomes the primary boot drive. It is also used to store system log files and diagnostic dump files.
- External media storage device—Depending on the system, the external device can be a CompactFlash card, a USB storage device, or an LS-120 floppy disk.
On MX80 routers, the internal NAND flash devices (first da0, then da1) act as the primary and secondary boot devices.
The external devices are emergency boot devices and can be used to revive a routing platform with damaged Junos OS. When these external devices are attached to the system, the router attempts to boot from these devices before it boots from the internal CompactFlash drive, the hard drive, or internal flash device.
When booting from the external emergency boot disk, the router requests a boot acknowledgment from you on the console interface. If you enter yes, the external media repartitions the internal primary drive and reloads the Junos OS onto that drive. When the loading is complete, the routing platform requests that you remove the external media and reboot the system. Once the reboot is complete, you must perform an initial configuration of the router before it can be used on your network.
