On Wed, 2003-02-26 at 12:46, Roy Souther wrote: > OK but what would you suggest that the RAID array be constructed with?
An external raid box. Drives, Redundant Power and Redundant Controllers. No PCs. > > Low cost PCs? Then you have the same problem. What if it fails? > A commercial RAID array server? It would be cheaper to buy two > licenses of the commercial software and run as virtual server. > > What would you use for your RAID array? > Costing more. That really depends on the commercial software, now doesn't it. BTW what advantage do you get having two licenses? Linux Virtual Server doesn't really work that way. Sure you can use it to offer two different servers with the same software running. But what if you want both servers to access the same information? The Linux Virtual server still has to share data. It doesn't magically happen. Either you share a raid array, you rsync between the servers or you store all your information in a database server that can be accessed by both systems. The solution I offered you uses Linux Virtual Server and is the closest to a fully redundant system you can get. Even with my solution, it will require time to fsck the drives before the second machine can take over. > On Wed, 2003-02-26 at 12:22, Mark Lane wrote: > > At 10:21 AM 2/26/03, you wrote: > > >For most data an rsync like solution would work just fine. The problem > > >with that is with files that are constantly being written to and changed > > >like database files. Partial data writes during an rsync can corrupt the > > >mirrors. Of course this is true of any thing but rsync would be slower > > >having to periodically scan the drive for any files that have changed and > > >may not sync files that currently open, locked and being written to. Using > > >a lower level of sync could allow the data to be changed simultaneously on > > >many systems without delay. > > > > I have follow this thread for a while and I think we are missing some > > obvious solutions here. Either that or I have just over looked them. > > > > You need to break the hardware system from the data in your mirroring. > > > > The data could be written to an external raid array with multiple > > interfaces. The raid array handles the information redundancy requirements > > and can be accessed by at least 2 machines. > > > > The machines run the exact same software which could be rsync'd to keep the > > same or could share system files from the raid array. One machine monitors > > the other machine using a heartbeat monitor as suggested by Maurice. (The > > second machine assumes the first machine's IP.) > > > > If one machine fails the other takes over and still has access to the same > > files. If a drive fails, your raid array doesn't > > go down. > > > > For full redundancy you would want a raid array with redundant power and > > controllers. > > > > regards, > > > Roy Souther > > www.SiliconTao.com > > > > Changing the way people do business. -- Mark Lane <[EMAIL PROTECTED]>
