Quick question really. We have a 4 server setup for our sharepoint farm and ive noticed that there are logs on each server. I thought that everything was written to the log that resides on the same server as central admin, but im not so sure now. Can someone offer some guidance on this?
The ULS (Universal Log system) maintains a different log file per server, see here http://msdn.microsoft.com/en-us/library/gg512103(v=office.14).aspx#bk_splog.
You could use tools such as ULSLogViewer(http://archive.msdn.microsoft.com/ULSViewer) for a real time solution, connecting directly via mapped folders, to all logs on servers.
For more advanced tracing, also Network Monitor is a good tool http://msdn.microsoft.com/en-us/library/hh372964(v=office.14).aspx, however is more complex, even with specific SharePoint targeted parsers.
General rule is that error is logged there it occured. But SharePoint can collect all the logs into one database for you. To enable this feature, go to "Central Administration" --> "Monitoring" --> "Timer Jobs". Change view to "All", and there you will find timer job "Diagnostic Data Provider: Trace Log".
Enable it, setup schedule and run. It will create ULSTraceLog view in the WSS_Logging database (could be called differently, as in my case):
Selecting data from this view will display your ULS logs, collected throughout all the servers in your farm:
P.S. Please don't forget that the database could grow considerably with time.