I have a server with 48GB or RAM on which I have installed RHEL5 with the xen kernel. I think maybe this is normal behavior, but the kernel only seems to be able to see 32GB. I looked around online, and I found very little. I think a significant data point is that xm info reports total_memory as 49142 (MB, I assume), which I suppose means that I can utilize the 48GB for my VMs?
We are currently considering a solution that results in a separate mount point for every user's home directory. Whereas we used to have at most a couple mounts per file server on a client, we now could potentially have hundreds of mounts, many from the same fileserver. This obviously impacts the client because there are many more mounts, and it also affects the fileserver, because there are tons more exports to keep track of. In our environment, we are talking about hundreds of clients per fileserver and hundreds of users per client (ie, probably no more than 10000 exports on a file server).
My question is specifically about the efficacy of this solution. There are other solutions we could implement if this one is bad, but for various reasons, some political, this one has risen to the top. The clients are all linux, and the fileservers are a mix of linux and solaris systems. The concern I have is that the resources the kernel has to track mounts and shares is finite, but I do not really have a good idea what its capabilities are.