> o Depending on how many clients you have, you might want to look at
> increasing the number of file descriptors on the servers. While
> xrootd is fairly economical with this (compared to the AMS, for
> example) the linux default of 1024 can be too small if you have more
> than 250 clients. (Given the defaults Andy put into the xrootd.)
> Obviously this is most important on the redirector machine.
Actually, the defaults are for optimization purposes. When shove comes to
push, xrootd will economically use all available file descriptors. Once it
runs out, we've found that strange things happen (at least on Linux) with
unexplainable hangs and some crashes. I've yet to determine what makes
Linux less friendly than Solaris when it comes to the FD limit.
The same can be said for the thread limit. Linux uses the process limit as
the thread limit (Solaris has no such limit for threads). Generally, it's
too small for more than a few dozen clients. In this case, you'll start
getting error messages in the log and xrootd will try to re-use any
available threads that it has. It should continue working but things will
Finally, you should make sure you have enough swap space. Here Linux is
better at it than Solaris. The general symptom is that xrootd can't launch
programs when it needs to. I recommend that you have at least 3xreal
memory reserved for swap space (on Solaris we recommend 16GB).