0.9m Data Disk Information

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LAST UPDATE 29 DEC 2011
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There are two computers, ctioa4 from which ARCON is run, and ctio36
which is typically used for web access, writing data to tape, etc.
The three disks on a4 are small (8 GB each), and cannot be made any
larger because of limitations of the SUN workstation required to run
ARCON (ARCON will not run on non-SUN machines, as far as we know).
Images, comprised of .imh and .pix files, taken by the 0.9m on ctioa4
are written to one of three disks:

on ctioa4	     /ua41    8.3 GB
		     /ua44    8.1 GB
		     /ua45    8.3 GB

To see how much space remains for data, type "disks" or "df" ("disks"
gives a faster response).  For programs that involve a relatively
small number of long exposures, these three disks are adequate for
multiple nights.  Programs that involve many images per night (such as
time-series data) or extending over many nights will have no trouble
filling these disks.  We estimate that you can take 2000 quarter chip
frames or 500 full chip frames before filling up a single disk
(less what's already on the disk, which is usually the problem)

If you find yourself approaching the disk limit, there are three
options.

(1) Shift to a different disk.  This is done by simply typing "cd
/ua##/v##" (where v## is replaced by your own visitor account number,
e.g. v12) in BOTH the Arcon Acquisition and Arcon Reduction windows.

(2) Move some data to ctio36.  The /u36# disks are much bigger than
the /ua4# disks, and are cross-mounted, so you only need to type
"imcopy *.imh /u363/v12/Night3", for example.  Once the data are
moved, you can delete them from the /ua4# disk and proceed.  NOTE: if
the /ua4# disk is FULL, you WON'T be able to move the data; so plan
ahead.  Also note that accessing /ua4# will cause ARCON to slow down,
so don't do this while observing.

DO NOT ATTEMPT THIS WITH STANDARD UNIX COMMANDS (e.g. cp).  RAW DATA
AT THE 0.9m ARE IN .imh/.pix PAIRS, AND ONLY THE .imh HEADERS ARE IN
THE ACQUISITION DIRECTORY.

on ctio36	     /u361   51.1 GB
		     /u363  615.3 GB

(3) Tape the data, or burn it to DVD.  The tape machines and DVD
burner are run from ctio36, but the /ua4# disks are cross-mounted
there, so you need not move your images to the /u36# disks in order to
tape them (for DVDs, it IS recommended to do this to avoid buffer
underruns).  Once they are securely written, they may be deleted from
the /ua4# disk and you can proceed.  Again, note that accessing /ua4#
will cause ARCON to slow down, and may have unusual consequences if
data is actually being taken.
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