Using Aips at the AOC

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Using Aips at the AOC

General Information

AIPS users should know the following tidbits:

For a hard copy of the AIPS Cookbook, contact Gayle Rhodes in AOC 267. If you're using AIPS, please read this document or ask your assigned friend for help before contacting the AIPS manager. If you need to do some programming for AIPS, Gayle also has hard copies of Going AIPS I & II.
Recording media is available in AOC 267 from Gayle Rhodes during work hours or in AOC 263 (the tape vault) after work hours.
Visitors are required to reserve a workstation before arriving at the AOC. The reservation calendar lists all the current AOC workstation reservations.
During working hours, we request you use psnet for plot files greater than 2GB. This prevents clogging the queues of other slower printers and your plot will come out faster.

AIPS and Tapes at the AOC

Tape Numbering

All public workstations and a number of other workstations have tape drives attached to them. Within AIPS, each of these drives is assigned a number, and is referred to using AIPS adverbs such as INTAPE and OUTTAPE. A list of the available drives and their associated numbers is given on AIPS startup, or, within AIPS, by typing TAPES. For instance, on a typical machine with one Exabyte drive attached to it, the TAPES command gives:

`Aips 1:`	`1. /dev/nst0`	`Exabyte TTi 8000`
`Aips 1:`	`2. on-line`	`real time FILLM (1)`
`Aips 1:`	`3. on-line`	`real time FILLM (2)`
`Aips 1:`	`4. (remote)`	`REMOTE TAPE`
`Aips 1:`	`5. (remote)`	`REMOTE TAPE`

INTAPE 1 is the local Exabyte drive, INTAPE 2 and 3 are for filling ongoing observations at the VLA, and INTAPE 4 and 5 are used to access drives on other workstations ( see Remote Tape Access below).

Local Tape Access

For an AIPS task or verb to access a tape drive, the drive has to be mounted using the AIPS verb MOUNT, e.g.,

INTAPE 1
DENSITY 22500
MOUNT

Always make sure to issue the MOUNT command well after physically mounting the tape: many drives need 30 seconds or so to get ready for access.

Remote Tape Access

In order to access a tape on a remote machine

set INTAPE to a number corresponding to one of the remote tapes (4 or 5 in the above example)
use adverb REMHOST to specify the remote machine, e.g., REMHOST 'ALFIRK'
use adverb REMTAPE to specify the tape number on the remote machine
type MOUNT

If all is well, this should be followed by a one-line message of the kind:

AIPS 1: Mounted on ANSI SCSI 2 tape (EXB-8500) on host alfirk.

TPMON processes

If upon MOUNT you get a list of error messages instead of the single line of the type above look in the next section for a list of common problems. Some of those problems can be fixed by manipulating the TPMON processes on the remote machine. For remote access to work, the machine with the remotely accessed drive requires the presence of n active processes TPMON1 through TPMONn, where n is the number of physical drives on that machine + 1. Killing and/or restarting TPMON processes can sometimes solve remote tape access problems.

Common remote tape problems after MOUNT

AIPS 1: ZMOUNR: UNABLE TO MOUNT REMOTE TAPE DEVICE, ERROR 96
AIPS 1: AMOUNT: TAPE IS ALREADY MOUNTED BY TPMON
AIPS 1: TAPE PROBLEM

The drive is in use by someone who failed to do a DISMOUNT in AIPS before unloading the tape.
Log on to the remote machine and kill and restart the TPMON processes (see next Section).

AIPS 1: ZVTPO2 connect (INET): Connection refused
AIPS 1: ZMOUNR: UNABLE TO OPEN SOCKET TO REMOTE MACHINE, ERROR 1
AIPS 1: ZMOUNT: ERROR 1 RETURNED BY ZMOUN2/ZMOUNR
AIPS 1: TAPE PROBLEM

Some or all TPMON processes are not running. Log on to the remote machine and restart the TPMON processes (see next Section).

Any AIPS message containing text such as device busy.

Some or all TPMON processes are corrupted. Log on to the remote machine and kill and restart the TPMON processes
(see next Section). It may be necessary to power cycle the drive.

AIPS 1: ZMOUNR: UNABLE TO MOUNT REMOTE TAPE DEVICE, ERROR 3
AIPS 1: ZMOUN2: error performing null op on tape drive
AIPS 1: TAPE PROBLEM

The tape in the drive is not ready yet, or there is no tape in the specified drive.
The latter can happen if you specified the wrong remote machine or the wrong drive number.

Killing and restarting TPMON processes

In some of the cases above TPMON processes had to be killed and restarted. In order to do so, log on to the remote machine *as AIPS* (this is very important) using ssh machinename -1 aips and type ps -elf | grep TPMON. If the TPMON processes are not all there, starting AIPS on the remote machine will restart them. Even if they are all there, sometimes the processes need to be killed and restarted. To kill the processes type kill n1,n2,n3 where n1,n2,n3 are the process ID numbers. Then, still on the remote machine, restart the TPMONs by starting AIPS. The system may complain you don't have a valid AIPS number, but the TPMON processes will be started anyway.

If you are unable to kill the TPMON processes check the owner of the processes listed in the first column after the ps -aux | grep TPMON command. If you are not logged in as that owner, either track down the owner and ask him/her to kill the processes or contact the Helpdesk to do this for you. For this reason, on public machines, it is important you restart any TPMON processes while logged in as AIPS, not as yourself. This will allow others logged in as AIPS to kill these processes at a later date, if needed.