Am 03.10.22 um 16:18 schrieb Olga Kornievskaia: > Hi Manfred, > > What's the purpose of segregating your connections? You don't want > your backup traffic "interfering" with your regular operation. > However, the assumption is that between 2 NICs the backup traffic and > regular traffic could co-exists, correct? In that case why not use > session trunking? What you are correctly experiencing is that with > 4.1+ the 2nd mount discovers that in the 2nd mount it's the same > server the client is talking to (even if it's thru a different IPs) > and the client will drop the new connection. > I did not know that I'm supposed to want this ;-) Sounds interesting. I searched for "replica" and "discovertrunking" but did not find anything. I'm on Linux 5.14 / nfs-kernel-server-2.1.1. Did you mean "nconnect" or is my Linux installation simply too old? Probably. 2.1.1 is 5 years old. I'm on openSUSE Leap 15.4, on idea why they ship such old userspace components. > For session trunking, you can configure your linux server (I'm > assuming it is, if not that might be a problem) to support session > trunking (by using replica=<> option). Then you can also add > "discovertrunking" option to your mount command and then the client > will discover the 2 available paths to the server. You wouldn't need 2 > mounts and you'd have both NICs available to serve your combined > regular and backup traffic. This would be the solution to utilize both > of the NICs (network paths) you have available between the client and > the server. > > > On Mon, Oct 3, 2022 at 9:27 AM Manfred Schwarb <manfred99@xxxxxx> wrote: >> >> Am 03.10.22 um 14:26 schrieb Jeff Layton: >>> On Mon, 2022-10-03 at 13:55 +0200, Manfred Schwarb wrote: >>>> Am 03.10.22 um 13:39 schrieb Jeff Layton: >>>>> On Sun, 2022-10-02 at 14:35 +0200, Manfred Schwarb wrote: >>>>>> Hi, >>>>>> >>>>>> I have 2 boxes connected with 2 network cards each, one >>>>>> crossover connection and one connection via LAN. >>>>>> I want to use the crossover connection for backup, >>>>>> so I want to be able to select exactly this wire when >>>>>> doing my NFS backup transfers. Everything interconnected via NFS4.1 >>>>>> and automount. >>>>>> >>>>>> Now the thing is, if there is an already existing connection >>>>>> via LAN, I am not able to select the crossover connection, >>>>>> there is some session reuse against my will. >>>>>> >>>>>> automount config: >>>>>> /net/192.168.99.1 -fstype=nfs4,nfsvers=4,minorversion=1,clientaddr=192.168.99.100 / 192.168.99.1:/ >>>>>> /net2/192.168.98.1 -fstype=nfs4,nfsvers=4,minorversion=1,clientaddr=192.168.98.100 / 192.168.98.1:/ >>>>>> >>>>>> mount -l: >>>>>> 192.168.99.1:/data on /net/192.168.99.1/data type nfs4 (...,clientaddr=192.168.99.100,addr=192.168.99.1) >>>>>> 192.168.99.1:/data on /net2/192.168.98.1/data type nfs4 (...,clientaddr=192.168.99.100,addr=192.168.99.1) >>>>>> >>>>>> As you see, both connections are on "192.168.99.1:/data", and the backup runs >>>>>> over the same wire as all user communication, which is not desired. >>>>>> This even happens if I explicitly set some clientaddr= option. >>>>>> >>>>>> Now I found two workarounds: >>>>>> - downgrade to NFS 4.0, clientaddr seems to work with it >>>>>> - choose different NFS versions, i.e. one connection with >>>>>> minorversion=1 and the other with minorversion=2 >>>>>> >>>>>> Both possibilities seem a bit lame to me. >>>>>> Are there some other (recommended) variants which do what I want? >>>>>> >>>>>> It seems different minor versions result in different "nfs4_unique_id" values, >>>>>> and therefore no session sharing occurs. But why do different network >>>>>> interfaces (via explicitly set clientaddr= by user) not result in different >>>>>> "nfs4_unique_id" values? >>>>>> >>>>>> Thanks for any comments and advice, >>>>>> Manfred >>>>> >>>>> That sounds like a bug. We probably need to compare the clientaddr >>>>> values in nfs_compare_super or nfs_compare_mount_options so that it >>>>> doesn't match if the clientaddrs are different. >>>>> >>> >>> >>> Actually, I take it back, clientaddr is specifically advertised as being >>> for NFSv4.0 only. The workaround for you is "nosharecache", which will >>> force the mount under /net2 to get a new superblock altogether. >> >> But clientaddr is silently accepted on NFS4.1+, and seemingly silently does nothing. >> >> The point is, RFC5661 explicitely tells >> "NFS minor version 1 is deemed superior to NFS minor version 0 with no loss of functionality". >> >> So this behavior comes as a surprise. >> >>> >>>>> As a workaround, you can probably mount the second mount with >>>>> -o nosharecache and get what you want. >>>> >>>> Indeed, nosharecache works. But the man page has some scary words for it: >>>> "This is considered a data risk". >>>> >>> >>> Yeah, it does sound scary but it's not a huge issue unless you're doing >>> I/O to the same files at the same time via both mounts. With >>> "sharecache" (the default) you get better cache coherency in that >>> situation since the inode and its pagecache are the same. >>> >> >> So I guess this is equivalent to the minorversion=1/minorversion=2 trick >> cache coherency wise then? >> >> >>> With "nosharecache" you need to be more careful to flush caches, etc. if >>> you are doing reads and writes to the same files via different paths. If >>> you need careful coordination there, then you probably want to use file >>> locking. >> >> Thanks for these explanations, it is appreciated! >> Manfred >> >>> -- >>> Jeff Layton <jlayton@xxxxxxxxxx> >>
