Mark Crispin wrote:
On Tue, 7 Nov 2006, Nancy Lin wrote:
Are there any free imap server solutions out there where it's NFS
safe? I did a quick search and it seems that cyrus isn't and dovecot
only kind of is. Maybe NFS just generally doesn't work?
You hit the nail on the head: NFS just generally doesn't work.
I apologize if I've tended to sound testy on the topic in recent
messages. I've spent the past 20 years of my life beating my head
against a wall getting NFS to "kind of work" for those people who
refuse to believe when I say "don't use NFS."
Mark, you do sound testy on the subject but it's ok ;-) At the risk of
irritating you further it doesn't help your argument by ignoring the
fact that there is a way to make it work successfully. You tend to gloss
over that fact which has the effect of irritating me since it does work
in the system I and others have constructed. Many things are about trade
offs and people who use NFS and get it to work (as we have done)
generally accept the pluses and minuses that go with picking that solution.
Again I don't refuse to believe you when you talk about NFS, I'm just
not doing the things that would get me in trouble. The only reason I got
involved in this thread was to see if I understood the pluses and
minuses of, as I see it, the two approaches to implementation. I would
really like to hear from you in particular on this. You see, I recognize
we have reached the limits of what I can do with NFS. I'd like to offer
my users more but it seems like in order to do that I have to accept a
single point of failure model. I had thought we were quite past the
point in time where that was considered an acceptable model in a large
enterprise type environment even if that is a University. Perhaps I need
to make things even more complex and use some sort of VMware scheme to
have virtual imap servers that can fail over for each other but again
it's another complex unproven approach unless someone on this list has
done that, please feel free to speak up. Does everyone just accept this
single point of failure issue without concern? I'm finding it a hard one
to sallow that with 40K users to support.
UW imapd goes through heroic efforts to keep traditional UNIX format
files from being corrupted when accessed via NFS. Among other things,
those efforts slow down the handling of traditional UNIX format files
for everybody, even those who do not use NFS.
Thank you for making it work if even in a narrow subset. Perhaps there
should be a compile time option to put in / take out NFS code that slows
things down. But that may be more work than it's worth since for
performance you should really use a different mailbox format.
David
--
David Severance
Network and Academic Computing Services
(949) 824-7552
[EMAIL PROTECTED]
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