RAID10
While it is quite possible to provide a RAID10 array by making some RAID1 arrays and combining them with RAID0, this approach has some problems.
Linux
Better read-ahead management and other file-open issues
NFS (prior to V4) does not have a concept of opening and closing a file. The Linux VFS does include that concept. So the NFS server has to open the file before a READ or WRITE operation, and close it afterwards.
Some funcitonality in filesystems and in the VFS assumes that the open/close requests that are passed down correspond to opens and closes by the application, and that a particular "file" structure belongs to a particular application (possibly a group of processes). Thus he current open/IO/close approach does not give good information to filesystems
More efficient COMMIT
The COMMIT NFSv4 (and NFSv4) request asked to sync a range of a file. However the Linux VFS only allows a whole file to by synced
RPCSEC/GSS
It would be really nice to have good RPCSEC/GSS support in nfs.
IPv6 support
It is possible that IPv6 support would be useful in nfs.
SMP afinity for threads and sockets
There is probably some value in assigning some processor or NUMA-node affinity to nfsd server threads and possibly to sockets as well
Dynamic thread count
The number of nfsd threads is currently static, though it can be changed from user-space.
There is value is having a dynamic number of threads. It means that the system administrator does not need to pick a number and hope it works. Even if the sysadmin is very clever, there will often be either too many threads, wasting memory, or too few causing uneeded delays. Having a dynamic number of threads means that the number can follow load.