In relation to building a Beowulf cluster, why is it necessary to create identical users on the slave nodes? If one were to create the users on the slave nodes in a different order to the order in which they were created on the master node, what problems would occur and how would one fix them?
I have been trying to find a concrete answer to this for a few hours but with no luck. Any help would be appreciate.
Probably because of SSH access/file permissions.
If one computer needs to access other it must have some sort of remote login technology, and SSH uses user names. Also if you have a file share between them, you may run into problems with file permissions when one pc writes them as one user and other tries to read them as other.
Regarding user creation, by default if you don't specify a user id your user gets the next available. In Ubuntu case, normal accounts start with UID 1000 so if you create 3 users you will get the following
USER NAME ID
user1 1000
user2 1001
user3 1002
If in a different machine you change the order, the users will have different user ids. Of course, you can avoid that providing the desired UID when you create the accounts.