Hello Christian, >From the keyboard of Christian, > Hi > > Much is written about High-Availability servers but I still didn't find a > good solution how to build two load-balanced webservers _without_ > connecting them both to one RAID (single point of failure). > > The problem with balancing between two servers is that the might host > web-servers that could write a file on system A and then reading this file > (status file or whatever) on system B immediately before e.g. rsync could > transfer it. In the worst case writing/reading could happen for two different > connection so that even connection based balancing wouldn't work. > > For now I have three ideas: > 1. forget about load balancing and do one-way balancing i.e. having one > primary and one minutely synced backup. In a case of a failure the > backup would take over the service and even if there's a little loss it > only occures at failures. > 2. use network attached storage. To avoid another single point of failure > you then would have to take two file servers and a protocol (NFS wont > need) to realize this. Maybe at least IP takeover and forced reconnection > NFS clients. > 3. Forget about writing anything to disk - apart from FTP uploads > everything will have to be written to database. But tell that your > customers.. > > > The ideal solution would be a network filesystem like www.inter-mezzo.org > but it does not appear to be really mature and tested in real life > conditions. > > So any idea?
Is drbd what you search for? http://www.complang.tuwien.ac.at/reisner/drbd/ Drbd is a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid 1 ..... But when I look deeper in it, it seems not to be the right thing: .... Currently drbd grants read-write access only to one node at a time, which is sufficient for the usual fail-over HA cluster. Although it is currently not on my task list, it would not be a great effort to allow both nodes read-write access. This would be useful with GFS for example. bye Waldemar -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]