Introduction
When you log into Lonestar, you are accessing one of two publicly available 'login' nodes. Identical to the compute nodes, these systems act as the front end for the entire high-performance cluster, and are shared among the several thousand users of Lonestar.
Appropriate uses for the login nodes
- Managing and moving files
- Compiling software
- Quick, serial, low memory computations (< 15 min)
- Managing your computing queue
Inappropriate uses for the login nodes
- Anything not listed above, especially long-running jobs
Exercise
While logged into a Lonestar head node, issue a top command. Notice all the different users on the system at the same time - if you overtask the login node, all these folks are inconvenienced. Luckily, we will teach you how to get the most out of Lonestar without spending much time on the login node at all!
Sample result
top - 21:07:16 up 22 days, 3:31, 112 users, load average: 1.58, 1.92, 2.35
Tasks: 668 total, 3 running, 660 sleeping, 4 stopped, 1 zombie
Cpu(s): 7.9%us, 0.4%sy, 0.0%ni, 87.5%id, 4.1%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 24675392k total, 23221856k used, 1453536k free, 19256k buffers
Swap: 0k total, 0k used, 0k free, 17171336k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
18615 pawelpap 18 0 70720 1796 924 D 67.1 0.0 77:34.34 rsync
1218 root 15 0 93740 4192 3228 S 13.3 0.0 195:30.89 sshd
18646 ercfrtz 15 0 68144 868 232 S 11.0 0.0 12:48.61 rsync
31311 root 15 0 135m 8744 3260 R 3.3 0.0 2:08.79 sshd
4128 root 15 0 0 0 0 R 0.3 0.0 344:17.60 ptlrpcd
4319 psherman 15 0 93588 4080 3232 S 0.3 0.0 0:00.26 sshd
13973 vaughn 15 0 13156 1576 824 R 0.3 0.0 0:00.15 top
31321 youpingc 15 0 40612 2524 1460 S 0.3 0.0 0:17.54 sftp-server
2915 ushnish 18 0 55912 3964 1460 S 1.0 0.0 0:05.01 scp
684 root 15 0 117m 6496 3044 S 48.8 0.0 8:59.97 sshd
2916 ushnish 15 0 59876 4744 2528 R 5.6 0.0 1:21.36 ssh
832 mhills 15 0 55916 3952 1444 S 5.0 0.0 0:22.97 scp
10408 chenjit 15 0 96424 3252 2056 S 1.0 0.0 0:00.03 vim
16558 root 16 0 122m 11m 3020 S 1.0 0.0 8:46.66 sshd
2915 ushnish 18 0 55912 3964 1460 S 0.7 0.0 0:05.16 scp
16709 ado 16 0 164m 98m 836 S 0.3 0.4 5:29.01 rsync
24049 tg457133 15 0 143m 80m 524 S 0.3 0.3 0:25.45 bash
30973 chang65 16 0 13160 1608 828 S 0.3 0.0 1:05.44 top
30986 jdietri1 15 0 58928 560 476 S 0.3 0.0 0:16.55 tail
