Telescope Data Center
Computing Resources

Sections:

• Compute Resources
• Sloan Digital Sky Survey
• Usage priorities
• FLWO, MMTO & Magellan raw data archive

Compute and Software resources

The Telescope Data Center makes available computers for the reduction of ground-based telescope data of all types. The older, conventional machine is named tdc and is a SunFire V880 with 8 750-MHz cpus and 32 GB of memory. It is managed by the Computation Facility with all their supported software available.

The TDC also has priority on 8 nodes of the hydra computing cluster. Separate accounts, as managed by the CF, are required to get onto this system. The cluster is located at CDP, so the TDC has supplied pool disk space at CDP, /pool/oircluster, for better I/O during cluster operations. It is only 738 GB so be sure to not fill it.

The tdc computer is open for use by anyone with a CF-domain account, and that has telescope data to reduce.

There are high-performance scratch disks available for those large data sets: /pool/tdc3 and /pool/tdc5. These are capable of I/O at over 70 MB/sec, and currently have 1 to 3 TB of space each. The /pool/tdc3 disk is restricted to OIR staff and students; only those in group oirgroup can use this disk. The other disk is open to anyone with a CF-managed account.

These disks are not intended for permanent storage, as they are not backed up and will be purged every week of data more than 90 days old. They are protected by parity and hot spare disks, so are more reliable than it might first appear.

In addition, for Megacam observers only, there is another scratch disk of 2.7 TB space, /pool/megascr1. You must be a member of the group megagrp to be able to use this disk. This disk is not currently being purged.

The above scratch disks are actually Raid-5 disk sets with a hot spare, so your files, even though not backed up to tape, will not be lost by the failure of a single disk in the set.

Sloan Digital Sky Survey

The majority of the "best" photometric database (not including the image thumbnails) and all of the spectral databases (as reduced at Princeton by David Spergel et al.) have been so condensed.

Follow the link: http://www.cfa.harvard.edu/oir/Docs/SDSS-cfa.shtml

Usage priorities

We are not currently trying to enforce the use of the tdc system to only those with optical and infrared ground-based data. We do have a priority order, however:

1. Reduction of MMTO, FLWO, and Magellan data
2. Non-CFA optical ground-based data reduction
3. Non-optical ground-based data reduction
4. Everything else

We are beginning to have to limit class 4 items, and have more than originally expected work that falls under class 2. As future MMT instrument data flows in, we expect we will need to be more restrictive about use of the tdc computer.

Note that the cfa0 computer is identical to tdc except for the size of its directly-connected scratch disk space.

Summary:
name:	tdc
cpus:	8 x 750 MHz
memory:	32 GB
Ethernet:	1000 Mbits/sec
disk:
	/pool/tdc3 - 1.3 TB scratch disk for oirgroup, 90-day purge
	/pool/tdc5 - 3.3 TB scratch disk, 90-day purge
	/pool/megascr1 - 2.7 TB scratch disk for group megagrp, no purge

Raw data archiving

Magellan data is contributed by observers and PIs and stored locally on disk and on tape. The TDC makes no other use of this data. There are two summary files of the data in this archive, one sorted by date: summary_DATE.db and one sorted by PI: summary_PI.db.

For FLWO and MMT data, see the summary table for details.