LIGO data on i2u2-data

See the LIGO Data Overview for info on how LIGO data gets to i2u2-data and LIGO Data Format for the data formats you'll find there.


"No data to plot"

1) restart

The "No data to plot" error on the e-Lab plotter page usually indicates that the Python server on i2u2-data is not active. It must be restarted manually every time the VM is restarted, and it's easy to forget. To restart, SSH to i2u2-data in a fresh terminal window and check its status:

$ ps -ef | egrep "|PID" | egrep -v egrep
root      1259  1258  0 Dec03 ?        00:01:21 python /disks/i2u2/ligo/data/streams/

If you don't see anything in the output of the grep, the server is definitely not running. Even if the server is listed under ps, though, it may still need to be restarted. First $ sudo kill it by its PID if it's running, and then

$ sudo su
# cd /disks/i2u2/ligo/data/streams
# nohup python
nohup: ignoring input and appending output to ?nohup.out?

The nohup command keeps the server running in the background. The command line will not return; just close the terminal window.

2) Check the data mount

Physics data on the i2u2-store01 server is mounted to the VMs as /disks/. If this mount is broken on i2u2-data, then the e-Lab will not be able to find any data and will return this message.

After logging into i2u2-data, try to list the contents of the /disks/ directory:
$ ls /disks/
If you see the i2u2/ directory, then the mount should be okay. If the directory is empty, however, the mount is broken. Remount it with
$ sudo mount -t nfs /disks
(the IP given is that of i2u2-store01). Then, restart the Data Server as above:
$ sudo su
# cd /disks/i2u2/ligo/data/streams
# nohup python

-- Main.JoelG - 2016-12-09


Topic revision: r4 - 2017-08-08, JoelG
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