We are using bigfile tablespaces for our temporary tablespaces on Exadata. My preference is to change this to use small file tablespaces for temporary tablespaces and to define multiple tempfiles for each temporary tablespace. My thinking is that this will eliminate some temp file contention we are seeing and will help with some parallel operations. I was looking to get a feel of how Exadata sites are configuring temporary tablesapces. I know each site will have different needs and setup will vary but I was just trying to get a general feel.
This is not really an Exadata-specific question, but more a function of workload. That having been said, I've this come up in an Exadata context when doing high-concurrency data changes, particularly unsynchronized RAT replays. The issue presented itself as a high number of buffer busy waits for block 2 (the LMT space management header block) of the single large tempfile. Createing a new temporary tablespace with many, smaller tempfiles resolved the issue.
MOS note 465840.1 also has some useful information.