Here is the steps to upgrade JunOS from RAM disk if you do not have enough available space on your disk, but you have enough memory free to use.
First, make sure you have enough free memory on your system:
Method1:
john@FW-GDBURTI-SRX-0> show system processes extensive
node0:
————————————————————————–
last pid: 15489; load averages: 0.14, 0.08, 0.08 up 10+23:35:46 18:27:00
124 processes: 18 running, 92 sleeping, 2 zombie, 12 waiting
Mem: 160M Active, 32M Inact, 560M Wired, 17M Cache, 112M Buf, 201M Free
Swap:
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
1114 root 7 76 0 490M 46780K RUN 0 820.3H 281.10% flowd_octeon_hm
22 root 1 171 52 0K 16K RUN 0 226.7H 86.43% idle: cpu0
23 root 1 -20 -139 0K 16K WAIT 0 170:59 0.00% swi7: clock
5 root 1 -84 0 0K 16K rtfifo 0 56:51 0.00% rtfifo_kern_recv
1120 root 1 76 0 4272K 1644K select 0 38:08 0.00% license-check
1117 root 1 76 0 9864K 3088K select 0 12:40 0.00% jsrpd
1119 root 1 76 0 9924K 3544K select 0 11:29 0.00% rtlogd
25 root 1 -40 -159 0K 16K WAIT 0 11:02 0.00% swi2: net
1111 root 2 76 0 20116K 5336K select 0 9:53 0.00% pfed
1104 root 1 76 0 31052K 4920K select 0 9:03 0.00% chassisd
1105 root 1 76 0 7140K 2500K select 0 8:04 0.00% alarmd
48 root 1 -16 0 0K 16K psleep 0 6:57 0.00% vmkmemdaemon
1101 root 1 76 0 2624K 744K select 0 6:31 0.00% bslockd
26 root 1 -16 0 0K 16K – 0 5:41 0.00% yarrow
1167 root 1 76 0 14640K 5500K select 0 2:53 0.00% mib2d
1168 root 1 76 0 12680K 5480K select 0 2:50 0.00% snmpd
41 root 1 20 0 0K 16K vnlrum 0 2:34 0.00% vnlru_
Method2:
root@FW-TEST1-MAO-UAC> show chassis routing-engine
node0:
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Routing Engine status:
Temperature 36 degrees C / 96 degrees F
CPU temperature 34 degrees C / 93 degrees F
Total memory 1024 MB Max 748 MB used ( 73 percent)
Control plane memory 560 MB Max 386 MB used ( 69 percent)
Data plane memory 464 MB Max 362 MB used ( 78 percent)
CPU utilization:
User 10 percent
Background 0 percent
Kernel 5 percent
Interrupt 0 percent
Idle 85 percent
Model RE-SRX240H
Serial ID AABG0967
Start time 2013-10-02 20:50:57 EDT
Uptime 19 minutes, 26 seconds
Last reboot reason 0x200:normal shutdown
Load averages: 1 minute 5 minute 15 minute
0.27 0.21 0.30
The unused part of control plane memory can be used to create a RAM disk. In the above example you can calculate it (560 – 386 = 174 MB free).
Other steps to create a RAM Disk
0. Login as root to shell.
1. Create tmp directory: “mkdir /var/tmp/disk1“
2. Mount it to RAM: “mount_mfs -s 200m md /var/tmp/disk1/”
3. Copy Junos image to /var/tmp/disk1
4. From CLI run update “request system software add
/var/tmp/disk1/junos-srxsme-11.4R5.5-domestic.tgz no-copy no-validate”
5. If you have managed to upgrade software on node-0 move to node-1 and upgrade Junos on it.
6. Reboot both nodes at same time.
Note: after reboot, the files in RAM disk will disappear automatically.