Writing ASP/GASP data to disk

GASP INSTRUCTIONS FOR OBSERVING 0737 AND WRITING TO DISK

I will assume you have setup the IFLO already so that gasp has power going to it. But an important thing to remember is that you make sure that the cal is OFF before you setup things up.

First, open maybe 3 xterms.

SET LEVELS ON GASP:

There are 4 columns:

-- the first two correspond to one polarization, controlled by converter rack module 11
-- the second two columns correspond to the other polarization, controlled by converter rack module 15.

You can tell the operator to adjust the attenuator setting in either converter rack module to change the power levels coming to gasp. The goal is to try to get the levels as close to 60-70 as possible. if they're a bit off that's ok, but *most importantly*, get the two polarizations to have approximately the same levels.

Gasp also now has attenuators that can be set from cpci (This can help alleviate the tendency to need very very large attenuator settings in the convertor rack.):

-- check current gain with "read_gain"
-- "set_gain (0/1) (dB)" will set the gain in poln 0/1 to your given number in dB. Range is -18.5 to +25.5 dB.

Now that you have levels set the way you like, onto the data taking.

PLEASE make sure you are in the correct directory for taking data:

go to /home/gasp/data/GBT06B-018/
type 'mkdir '
(see the directories in there to see how I've named them)

This is the directory from which you will be running the datataking routines and scripts.

CAL DATA:

Depending on which source you're taking a cal, $freq is 820 or 1400, depending on the reciever you're using.

run 'stat_msg' in another window. this is important: the scan has started once each dataserver has reported back with the MJD. This MJD *must* be precisely the same between all dataservers.

-- If it is, then good, let the scan go.
-- If not, then cancel the scan by typing 'stop_asp' in any gasp xterm, or by ctrl-c'ing the scan in the window you ran the script. ctrl-c out of stat_msg. wait a minute. start scan again, again making sure of the start MJDs.

It is rare that the MJD don't match, but it does happen on occasion.

Again, remember to run all these from the datataking directory.

The scan will produce 2 30-second integrations, then quit.

Turn cals OFF.

0737 WRITE TO DISK:

/home/gasp/config/GBT06B-018/$freq

where $freq = 820 or 1400.

You will first run a setup script. These scripts are called:

'record_setup_data'
'record_setup_data.cgsr'
'record_setup_data2'
'record_setup_data2.cgsr'

These correspond to the disk you are writing to, /data/ or /data2/, and whether you are including the cgsr nodes as well.

We'll start by taking data on /data, since it corresponds to the most nodes with writeable disks. Once it runs out of space, switch to the /data2 disk. More on that below.

Also, you should start by using the cgsr nodes, and stop once they are full. More on that below, too.

the usage for the script is:

record_setup_data obs freq

obs is the observation number (1 to 8)
freq is the observing frequency (820 or 1400 only for now)

it will not run if # args !=2 or if obs is not between 1-8 and freq is not 820 or 1400.

when you use this, just keep incrementing each time you start a new scan, even if you switch disks. This number will correspond to a subdirectory on the nodes' disks to which this raw data will be written.

Once this script is run, everything is put into place (the config files, etc.) and ready for the actual datataking to begin. To do that, follow the command sequence:

> start_record

wait till it's done, wait a few more seconds, then type

> start_ds

again, wait till it's done, wait a few more seconds, then type

> go

This will write the raw data to the nodes, until you stop it.

Again, run stat_msg in another window to see that (a) the scan has begun and (b) that the MJDs for each dataserver *match*.

So to stop the recording, you type 'stop_asp'. There are two reasons to stop recording (apart from the observing time being over):

(a) you've run out of disk space and need to switch to the other disk
(b) it is time for an eclipse

SWITCHING DISKS:

To check the disk space situation, type 'node_disks' to check the gasp nodes, and 'cgsr_disks' to check the cgsr disks.

'node_disks' is like a df command on each node. Output is:

----> node1
/dev/hda10 233778740 158121912 75656828 68% /data
/dev/hdc1 241263968 223168396 18095572 93% /data2

----> node2
/dev/hda10 233778740 152857720 80921020 66% /data

----> node3
/dev/hda10 233778740 204021080 29757660 88% /data
/dev/hdc1 241263968 183177524 58086444 76% /data2

...etc...

/data and /data2 are the disks. when any one node gets to 100%, then you need to stop the scan and switch to the 'record_setup_data2' script.

'cgsr_disks' ouput looks like this:

----> cgsr3
/dev/md3 458242392 453114668 472252 100% /data

----> cgsr4
/dev/md3 458296528 396403592 57236904 88% /data

----> cgsr5
/dev/md3 458296528 361881764 91758732 80% /data

...etc...

(we get access to cgsr3 to cgsr20)

We only get one disk on cgsr, so when one of them gets full, you need to stop using cgsr to take data.

ECLIPSES: