Observing Operations | Reviews | Survey Management

Sloan Digital Sky Survey
Review of Observing Systems and Survey Operations 

Configuration Management for the Operational Systems
Ellyne Kinney
April 19, 2000


 

The Configuration Management procedures for the operational systems have evolved over the past year from a rather unstructured environment that optimized developer convenince, to a more formal environment that includes formal tracking, handover and testing of each software package. Currently testing is planned for 3 nights before each dark run with occasional testing during the dark run when needed to test critcal bug fixes. As development and bug fixes wind down it is anticipated that testing can be reduced to only 1 night per dark run, and that bug fixes and testing during the dark run would be extremely rare.
 

Configuration Management Tools

Source Code Control System

All software developed at Fermi Lab and most of the code developed at other Sloan Institutions is stored and tracked in a source code control system. The system in use for Sloan is CVS (Concurrent Version System. Each software package is stored as a separate module in a central source code repository located on a computer a Fermi Lab. The CVS system allows us to create a stable release of a software package by creating a branch in the repository for that software modules. Branches are typically tagged with a version number and only bug fixes for this version of the software module are made on this branch. After a few test and bug fix cycles on this branch a stable version of the software module should develop. Meanwhile enhancements and ongoing development of the software module can continue in the main line of the repository. The branch and the main line are periodically merged by the developer so that the bug fixes make it into the enhanced versions of the software module.
 

Product Database

CVS does a good job of tracking changes to flat ASCII files such as source code, but is award to use for tracking compiled binary sources or for switching between different versions of software packages. For this task we use a Fermi Lab developed database and tracking tool called UPS (Unix Products Services). In the UPS system each software package/module is called a product. All products in the UPS are cataloged in a simple ASCII database and are stored in a special Unix file partition (/p). Each product has a sub-directory in the /p partition, where several complete versions of each product can be stored. This database makes it straight forward to switch between different versions of a product and to track the software dependencies for products.
 

Problem Report Database

All Problem Reports (PRs) for both Software and Hardware are tracked using a Web-based Problem Report System called GNATS. PRs in GNATS can be classified as critical, serious or non-critical. Critical software bugs are defined as a problem that prevents telescope operations or makes reducing the data impossible. All critical bugs are fixed immediately and the fixes are tested right away. Serious bugs are problems or bugs in important telescope commands or operational tools, but for which there is a known work-around. These bugs are fixed in time for the next dark run. Non-critical bugs are defined as enhancements to the current software package or are reports about annoying features. Non-critical problem reports are typically resolved in a 1-3 month period. Change requests are also filed in the GNATS system and are flagged as change requests. In the event there is a disagreement between the development team and the observing team about change requests or the classification of a serious/critical bug. Chris Stoughton will take input from both teams and make a recommendation to Bill Boroski and Jim Gunn who will make the final decision.
 

Basic Procedures

Upgrading Software on the Operational Computers

  For mature software that is not under active development and has only occasional releases due to minor bug fixes, the developers at FNAL compile the code at FNAL and install the software into a UPS database on a FNAL computer. The observers can then install the software to the local UPS database via a simple install script. Software packages that follow this upgrade strategy include dervish, astroda, and murmur. For the TCC, which runs under OpenVMS on dec Alphas, the developer takes care of the installation for the observing team, but coordinates his upgrades with our Bright Time/ Dark Run cycles. For software packages that are still under development, such as IOP/SOP and the MCP/TPM we have developed the following hand off strategy

 When the programmer has some changes that need to be tested, the software module is checked into the source code repository, and tagged with a version number. E-mail is then sent to the observers with the version number and release notes that explain the changes that have been made to the software module.

 A branch in the source code repository is created. Bug fixes to the software module are made on the branch and the programmer can continue to work on other development on the mainline of the source code repository. This will allow development to continue even if the new software module right away cannot be tested right away.

 The software module on the branch of the source code repository will be checked out by an observer and compiled. The software module will then be declared to the local UPS database as a test version.

 The observers test the software module. The release notes help the observers determine what is most important to test.

 If there are bugs found in the software module, the programmer will be notified of the problem though the problem report database. Code changes to fix the bugs will be made on the branch in the source code repository. Once the bugs are shaken out of the test version, the branch in the source code repository will be merged back into the mainline in the repository. A new version of the program will be declared as current to the UPS database and an e-mail sent to a general mailing list about the change.

Monthly Cycle for Software Upgrades

 1-2 days after a Dark Run the Observers, the Developers and the Data Processing team will meet to discuss problems that were encountered during the Dark Run and to set priorities fixes and enhancements to the software.

 During Bright Time there will be some opportunity for the development team to troubleshoot and test the development version of the software packages on the operational system. Arrangements should be made ahead of time with the observing team for testing support.

 3 days before the Dark Run shakedown testing begins. In the source code repository a branch will be made for any software module requiring bug fixes. All bug fixes are made on this branch. The goal is to find as many bugs as possible during this time. The most stable version of each software module will be made current in the UPS database at the end of the shakedown tests.

 uring the Dark Run all operationally critical software will be frozen. This means we will only run with the tested current versions of the software in the UPS database. If a critical bug is found in a software module it will be fixed on the branch of the source code repository and tested before science observing resumes. The new software module with the bug fix will be made the current version of the software module in the UPS database once the module passes testing. If a bug is found that is serious or non-critical it will be fixed on the main line of the source code repository. Further development of the software may also continue in the main line of the source code repository. Bug fixes made on a branch on the source code repository will be merged into the main line periodically by the developer.

 Sometime during the last 1-2 nights of the Dark Run the observers may be available to test new versions of software modules while the moon is up.


 Review of Observing Systems and Survey Operations
Apache Point Observatory
April 25-27, 2000

 
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