I am trying to research options for a scalable mail-server setup.
Inquiries to a Sun/Solaris mailing list returned very little
feedback, so I figured I would ask here, as some of you might have
had to tackle a situation like this.
I am looking at using Fibre Channel to interface with a storage device.
The reason behind this idea was not because of faster disk access or the
now relatively low cost of Fibre Channel equipment, but because of the
support for having multiple servers on the FC-AL loop. Ideally what I
would like is something like this (scaled down to simplify example):
| server-A |-------| drive array |-------| server-B |
Where server-A and server-B have the drive array, which will be
set up as a single partition, mounted read-write as /var/mail
for mail-spool storage. The servers will have their own internal
system disks. Assuming that any program accessing the mail
spools locks the spool via fcntl(), would this be possible?
Would server-B see a file as locked if it is locked via fcntl()
on server-A? Or would I need Veritas or DiskSuite to accomplish
something like this? And no, NetApp is not a solution my client
is willing to entertain.
I was told this regarding file locking:
File locking mechanisms (such as fcntl and flock) are for the most part A)
Purely advisory in nature, and B) Within the process. When a process
fcntl()'s a file descriptor, you must remember that the fd is unique to
only that process.
That seems to conflict with my daily experience with Exim and several
different POP3 daemons. If exim has the spool locked, either while
delivering mail or via exim_lock, the POP3 daemons cannot lock the
spool and return an error to the user. Can anyone shed light on this
concern as well?
Any help or pointers would be greatly appreciated.
-F
