[daip] data disks

[Eric Greisen]

Dr. Sylvie F. Beaulieu writes:
 > Quebec, 8.March.2005
 > 
 > Hello Eric,
 > 
 > Ok, then, let's say I have two users: user1 and user2 and they
 > have their "aipsdir" in  /home/user1/aipsdir  and 
 > /home/user2/aipsdir,  which is the area seen by "mcat"
 > which is different than a directory where they would put their
 > fits files i.e. the data before being processed by aips.
 > 
 > Then, how can I just fill in those area in the DADEVS.LIST file
 > so that each user, no matter which machine they use, will always
 > have access to their area? this is the bit that is nebulous to me.
 > 
 > Is the "aips da=/home/user1/aipsdir"   the same as doing:
 > setenv MYAREA /home/user1/aipsdir  ?

    This is not the correct grammar.  It is da=<computer_name> to get
the disk areas assigned to the computer named <computer_name>.

 > 
 > How does aips know how to distinguish between one user
 > and another ? is it only by the id number they choose at the
 > beginning of a session? 
 > 
 > What happen, let's say, if two users use the same id number?

I am having problems figuring out what your mental picture of the disk
set up is.  Are you proposing to have on some central computer many
disk areas, one per user?  But these users will actually be running on
multiple different computers with the same person using different ones
at different times????

That is messy.  If the user has in his/her home disk area a file
named .dadev  (note the dot), then that file describes that users data
area.  Of course, if you do this, all hope of central administration
is lost and you will never again know what anyone is doing.  Note that
this .dadev file could select any disk area anywhere by any name if it
has a + in column 1.  It sounds to me as if you will need to go to
this usage however.

A user should not select user numbers at random.  If they do, then
they will not get their data of yesterday today.  If multiple users
are using the same disk area, then numbers have to be assigned since
that is the only way to separate data.

Note that the $AIPS_ROOT/DA00/<host_name> directories should really be
on <host_name>.  Linux has file locking problems over NFS.

Eric Greisen