Administration
Step 1 - Deciding if the Grid Will Need a Slave GTS
Most of the services available on a grid are there because they perform a function that is needed by the grid's users. However there are a few services that are needed as grid infrastructure. The Dorian service is needed to issue credentials to users that prove their authenticated identity. Since the user credentials issued by Dorian are normally valid for twelve hours, a single instance of Dorian can support many users.
Another service that is needed for grid infrastructure is the Grid Trust Service (GTS). The purpose of GTS is to tell the other grid services and clients what instances of Dorian to trust and if any credentials issued by a trusted Dorian have been revoked by that Dorian. Since other services and clients will ask GTS for updates every few minutes, a moderately large grid may overwhelm a single GTS service.
To avoid the grid-wide performance problem that an overwhelmed GTS would cause, the installation instructions for caGrid describe how to configure a grid with a master and slave GTS. When configured this way, only the slave GTS gets updates from the master GTS and everything else gets updates from the slave GTS.
Having a grid with a master and slave GTS allows for the GTS to support a much larger grid. There can be multiple slave GTS instances in a grid. When grid growth causes the slave GTS to approach its capacity, you can add an add another slave GTS.
Including a slave GTS in a new grid configuration makes the grid more complicated to set up. If you expect your grid to grow indefinitely, then it is best to configure it with a slave GTS now. If you expect that grid to have fewer than 40 services and only a moderate number of clients at any one time, then you can save some time now by including only a single GTS instance in your grid.
The decision to not include a slave GTS in a grid can be changed after the grid is in production. However this change will require making the grid unavailable for a short time and the change process is not yet well documented.
Based on these guidelines, decide it you want to configure your grid with a single GTS or a master and slave GTS.
