--On 7 June 2006 15:26:48 -0400 Barry Warsaw <[EMAIL PROTECTED]> wrote:
> >> I'm looking at running Mailman on a cluster of servers, sharing a >> single disk with Apple XSan. >> >> I presume that everything done through the web interface must be >> resilient to multiple simultaneous attempts to modify - say - a list >> membership. So, I expect that I can put the list databases on a >> shared file system. > > Mailman's locking scheme is NFS-safe, and should be safe on all shared > files systems that support POSIX semantics. Given this, there should > be no race conditions against the list databases, through any of the > access mechanisms. Just make sure that if you have really huge lists, > your cgi timeouts are set appropriately or your web server could kill > the Mailman cgis while they wait for some other process's list lock to > be released (this is the case even if you weren't clustered). Make > sure your list lock timeouts are set appropriately too because you > really don't want them getting broken. That's good. It's an essential requirement that all the web servers see the same information. >> But, what about the queue runners. Is it safe to share the queues >> between servers? If its safe to run multiple queue runners on one >> queue on one machine, then I should be OK - but I'm not sure that >> Mailman does that. If not, then I'm probably safer leaving the queues >> on unshared file systems, and accepting that a some queued items >> won't get processed while a cluster member is unavailable. > > This should be safe too. Mailman uses a sha1 hash space slicing > algorithm to ensure that each qfile is managed by exactly one qrunner > process. No locking is required as long as you configure your slices > appropriately. It's still the case though that should a cluster member > go down, that portion of the hash space managed by those qrunners won't > get processed. It should be fairly easy to reconfigure a backup though > to handle the hash space while the primary is off-line. OK, so I have to figure out how to configure the slices to avoid clashes, but still won't gain anything until I figure out a backup scheme. I have failover between cluster members, so that should be doable. On the other hand, I might just live with the downtime - cluster members don't tend to go off line for more than a few minutes. Thanks Barry. I feel like I know what I'm doing now! > - -Barry -- Ian Eiloart IT Services, University of Sussex _______________________________________________ Mailman-Developers mailing list Mailman-Developers@python.org http://mail.python.org/mailman/listinfo/mailman-developers Mailman FAQ: http://www.python.org/cgi-bin/faqw-mm.py Searchable Archives: http://www.mail-archive.com/mailman-developers%40python.org/ Unsubscribe: http://mail.python.org/mailman/options/mailman-developers/archive%40jab.org Security Policy: http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq01.027.htp
