Stan Hoeppner wrote: > IMO, the best way to do high availability is to use an active/active > cluster of any number of nodes you see fit to meet your performance > and reliability needs. All hosts are live all the time and share he load. > When one goes down client performance may simply drops a bit, but > that's about the extent of the downside. > > It's inherently more straight forward to setup than the previous > scenario, especially if you're using NFS storage. In this case, you'd > build two identical Dovecot servers and have each mount the same NFS > mail directory. Read the list archives for ways to mitigate the index > file issue. Timo wrote a new director specifically to meet this need. > > Two other options for the shared storage are a fiber channel or iSCSI > SAN, or using DRBD to mirror disks (or logical devices--RAID) over the > network. Both of these solutions require using a cluster filesystem > such as GFS2. These can be quite a bit more difficult to setup and > get working properly than the NFS method, especially for less > experienced sysadmins. They can also be more difficult to > troubleshoot, especially for sysadmins lacking sufficient knowledge or > aptitude with regard to storage hardware and low level Linux device drivers.
Stan, what do you think about GlusterFS or Ceph? I am looking for a high available AND scalable solution based on distributed/replicated storages (maildirs). I am not talking about a simple NFS export or something like this. A real-time replication managed by dovecot would surely be the best way to keep data in sync and balance clients. -- Sven
