[daip] error in catalogue file

[Eric Greisen]

Ruta Kale writes:
 > Dear Sir/Maam,
 > I have 3 disks in aips and i was working in disk 2.
 > After running imagr ,i received the message UVOPEN ERROR
 > cannot find the uvdata and task did not run.
 > Then i found that doing indi 2,and 'uc' or 'mc'
 > it gave a message: ZOPEN: STILL TRYING TO FIND FILE CAD0000
 > i could not even exit aips once i go into disk 2 from my user id.
 > i logged in with other user ids .all the disks were working fine there.
 > Finally to resume my work i copied all the files from disk 2 to another new
 > disk and
 > just commented the disk 2 in .dadevs file.then everything worked fine.
 > Can you suggest a solution to the problem that i was facing?

I suspect the actual message was 
   ZOPEN: STILL WAITING FOR FILE CA......
since the message you show does not occur.  This message comes when
some process in the system has the file locked and another process
(your aips running mcat) tries to open the file.  The best fix is to
find and kill the offending process.  A reboot should dod this. The
second best fix - which you used - is to make copies somewhere and
stop using the locked file. there is a bug in Linux file locking if
the data area is now physically resident on the computer that is soing
the computing.  When a process dies while having locks, those locks do
not always close across the NFS (network file system).

Eric Greisen