On Wed, Mar 20, 2019 at 11:05 PM Marvin Zhang <fanzier@xxxxxxxxx> wrote: > > On Wed, Mar 20, 2019 at 10:29 PM Olga Kornievskaia <aglo@xxxxxxxxx> wrote: > > > > This question is more of an NFSv4.1 protocol question thus I would > > encourage you to ask it on the nfsv4@xxxxxxxx. > > > > On Tue, Mar 19, 2019 at 11:06 PM Marvin Zhang <fanzier@xxxxxxxxx> wrote: > > > > > > Hi Experts, > > > Here are some questions about trunking: > > > 1. For session trunking. During first mount(or first connection), > > > client create a session. During the second mount(or second > > > connection), client will reuse the session which the first connection > > > created. Does the second mount create a new super block or reuse the > > > previous? > > > If there is a READ request on this session, how to judge to > > > use which connection? > > > > Session trunking does not require the client to create a different > > mount in your example. A single mount could have multiple TCP > > connections established between a client and a server and they would > > use the same NFSv4.1 session to send operations to the server. A read > > operation issued by the application using the NFS mount could use one > > of those connection and the question which one it would use is > > protocol implementation specific. Simplest implementation round robins > > connections for incoming RPC tasks. > I just followed this article: > https://packetpushers.net/multipathing-nfs4-1-kvm/ . In this article, > client mounts the server twice in differ conections. But as you said, > it's not session trunking. I still don't konw how to mount a server > only once with two connection. Could you give me a sample here? I > don't find any example in google searching result. There was a series of patches proposed by Trond about 2 years ago that add "nconnect=X" mount option that will create X TCP connections to the server. You can find that series apply it and build a kernel with that or you can use SLES15 distro where those patches were included. > > > > > If the client mounted a server and then decides to mount the same > > server again (given same mount options and credentials), in the linux > > implementation, the existing NFS client (and its TCP connection) would > > be re-used. Thus it would not be a case of session trunking. > > > > > 2. For client id truking. As protocol said, client can create multipl > > > session at the same time. I can't understand in which scenario client > > > can create multiple session > > > > Again IETF list can provide some examples and motivations for the > > clientid case. I think perhaps it was for the clustered server > > environment where the client would use the same client id across > > different cluster nodes but it would establish unique sessions to the > > nodes.
