I was reading an article on Linux Journal about Memcached and it mentions Netbooting multiple servers off a single root image:
LiveJournal's Web nodes are all diskless, Netbooting off a common yet redundant NFS root image. Not only is this cheaper, but it requires significantly less maintenance.
How does this work with logging? Does each node write to the same place? What about configuring static ip addresses? If machine A writes to the disk, does machine B pick it up? When he says "web node" does he mean just the web server? I'm assuming this means the web application as well (PHP/Perl), correct?
Is this even a good idea (with mostly using RAM)?
Can this same thing be done with iSCISI?
Logging would typically be done by setting up the syslog to write to a central location over the network. syslog can do this with minimal changes. The server syslog has to be configured to accept TCP connections, the clients then are told to write to that server.
For things like Apache, you'd probably have it write to different directories based on the name, or you could pump it to syslog or something...
Is it a good idea? Sure, works great!
The same thing is not as easy to do with iSCSI, you'd have to have the root partition be on a clustered file-system such as OCFS or GFS, iSCSI is not a file-system, it's a networked block device.