NFS futures at LOSUG
By user12625760 on Apr 19, 2007
We were privileged to have the legendary Calum Mackay talk at the London Open Solaris User Group last night on the topic of NFS futures. Including everything that is in the up coming NFS v4.1 specifications:
Parallel NFS aka pNFS
He also covered the rest of what is going on with the NFS v4.0 work. In particular the namespace work that he has been doing which will provide Mirror mount support and Referrals.
Mirror mounts will change the way a client behaves when it encounters a directory that is a mount point for another file system on the server. For example given 2 file systems:
/export/home/cjg and /export/home/cjg/Documents
Currently if you mount /export/home/cjg from a server using NFS v2 or v3 on an NFS client and look in the Documents directory you should see an empty directory which if you then write into can cause loads of confusion and potentially more serious consequences.
However with NFSv4 & mirror mounts now you see something different. The client would automatically mount the sub file systems without recourse to the automounter. This is kind of cool as the layout I describe above is exactly what I want for my home directory. That way when gnome or firefox or thunderbird go pop and corrupt their start up file I can roll back to the last snapshot without it messing up my data that is in Documents.
Referrals have the potential to be as useful and I suspect also the potential to be as dangerous as symbolic links. They allow you to move a file system onto another server and yet the client application can continue to access the original path. The client kernel gets sent a referral and mounts the file system from the new location.
All in all an excellent evening.