On Server Fault, we were discussing this question in chat. There are non-native speakers in the chat and somehow we got on the topic of grammar and proper use of commas.
The sentence of interest:
I have just got a new Ubuntu LAMP VPS server, which I am trying to configure.
Some people thought that the comma was superfluous. Others did not.
When is it appropriate for a comma to preceed the word which, and is the example sentence above correct?
Also, before you vote to close this question as a dupe of this, please consider the differences between the two questions and ignore the similarity of the titles. The OP's example sentence was restructured in that question instead of addressing the proper use of commas.
Supplementary (or non-defining, or non-restrictive) relative clauses are by convention set off by commas and integrated (or defining, or restrictive) relative clauses are not. The clause in the example, 'which I am trying to configure', is a supplementary relative clause, so the comma is appropriate.
You can generally distinguish a supplementary relative clause from an integrated one by seeing whether or not you can detach the relative clause and still be left with a meaningful sentence. With the example, you can say simply 'I have just got a new Ubuntu LAMP VPS server' without the clause 'which I am trying to configure', which is a piece of bonus information. However, if the example had been 'I'm not getting anywhere with that new Ubuntu LAMP VPS server which I am trying to configure' the relative clause is essential in identifying exactly which new Ubuntu LAMP VPS server is being discussed. 'I'm not getting anywhere with that new Ubuntu LAMP VPS server' on its own doesn't tell us.Tweet