[daip] question about CDs and DVDs vs tapes in AIPS

[Eric Greisen]

RALLIS at mps.ohio-state.edu writes:
 > Is it reasonable to run AIPS for VLA data without a DAT or Exabyte tape drive?
 > That is, to use ftp, CDs, and DVDs to get and distribute data and to use
 > CDs and DVDs for backups? Writing the equivalent of a FITS tape on a CD is 
 > then a two-step process: first use AIPS to write FITS images to disk outside
 > of AIPS and then write the set of files to a CD. A bit more cumbersome than
 > writing directly to tape (and takes up more disk space) but not necessarily 
 > slower. 
 > 
 > I plan to upgrade my computer and version of AIPS. As my exabyte drive is
 > reaching the end of its useful life, the issue is whether I should buy
 > a new tape drive for AIPS. Am I missing something here? Space Telescope and 
 > Chandra send data on CDs and DVDs. Without a tape drive, is there still
 > an advantage to a SCSI disk?
 >                                              - Michele Kaufman       
 > 

There is both an AIPS memo and an article in the latest AIPSLetter on
the subject of DVDs.  In principle, they can be used as a slowish disk
within AIPS, either a read-only disk or even read-write.  There has
been some serious difficulty getting working drivers for the type of
disk system required under Linux unfortunately.  Greg Taylor's
particular system and drive work well, but the ones we got for the
public Linux boxes do not.  The two-stage scheme you describe does
work of course using a mode windows-like disk system on the CDs and
DVDs. 

All aips tasks now read data from disk as well as tape so that is
covered.

See the aips web page for access to the memo and AIPSLetter:

         http://www.aoc.nrao.edu/aips

Eric Greisen