To transparently archive the raw data
from all KPNO/NSO nighttime
telescopes on Kitt Peak. This has recently expanded to include data
from CTIO, as well. The WIYN telescope board has approved a CDrom based
upgrade to Save the Bits that will also serve as the
primary data distribution mechanism for the telescope, in addition to
the archival functions. The central data center for both CTIO and WIYN
is at NOAO headquarters in Tucson.
Current Status Reports for Kitt Peak National Observatory
The Archive
status reports the current state of the archive queue and tape drives.
The KPNO
domes report summarizes the health of the queue and disk space in
each dome, as well as lists the latest archive transactions from each
telescope computer.
To request data from the Save the Bits archives,
you may fill out the provided
web-based
form. Post-proprietary access to the data will only be provided
on a case-by-case basis while scientific grade database facilities are
being implemented. If you have any questions, please contact Rob Seaman
at the address, email address, or phone number below.
During the first full year of operation, Kitt Peak telescopes archived
a little over 400 Gigabytes of imaging data. This represents 224,000 images.
The Save the bits FITS header catalog for a year's images
approaches a half Gigabyte, the index that cross references the archive
tapes and the catalog is about 10 Megabytes/year.
Allowing for the WIYN telescope which will begin regular operation
(and archiving) this year, and also compensating for the fact that the
IR instruments on Kitt Peak were only archiving their data for half
of the first year, a comfortable estimate is
one-half Terabyte and 250,000 images/year.
Basic Design
The domes feed a central archive, queuing is provided by a unix
print spooler.
Tape Format
The archive tapes are written using exabyte 8505 FITS image
extension format, about 4 Gigabytes per tape. A number of images
are concatenated from the various telescopes and packed into ~50 Megabyte
tape files.
Catalog
The headers are written to the catalog file, a separate index
cross references the catalog and tapes.
Multiple Drives
An lpd filter, bitf , writes the tapes and swaps
automatically between an arbitrary number of drives.
Swapping Tapes
The bitmon program provides archive and dome status
information, and allows for swapping tapes. The Observing Tech staff
are responsible for swapping the archive tapes daily.
Recovering Data
Although not the main purpose, 24 nights' data had been
recovered following observer mishaps after the first year.
One observer had his data stolen from his office!
System requirements
The archive hardware requirements are minimal - a networked
workstation with one or more tape drives. Unix and a Berkeley style
line printer daemon are system requirements, although a similar
design would be workable on many other platforms. NOAO currently
runs the archive under SunOS 4.1.3, and will support Solaris operations
in the future using the System V printer daemon.
bits have been saved.
