> -----Original Message----- > From: Trond Myklebust [mailto:Trond.Myklebust@xxxxxxxxxx] > Sent: Tuesday, January 18, 2011 11:15 AM > To: Matt W. Benjamin > Cc: Muntz, Daniel; rees@xxxxxxxxx; androsadamson@xxxxxxxxx; > linux-nfs@xxxxxxxxxxxxxxx; Benny Halevy > Subject: Re: 4.1 no-pnfs mount option? > > On Tue, 2011-01-18 at 13:46 -0500, Matt W. Benjamin wrote: > > Hi, > > > > Isn't by mount a plausible way to select for pnfs > independent of debugging? Is it assured that a client > administrator would never reasonably wish to do this? > > "Why would an administrator never want to do this?" is not a helpful > question. > > A more useful question is "what reason would you possibly have for > overriding the server's request that you do pNFS when your client has > pNFS support?" What makes pNFS so special that we must allow > administrators to do this on a per-mount basis? By the same logic, why should a user be allowed to select which version of NFS they use for mounting when the server has a perfectly reasonable way of negotiating it? Getting to choose v2 vs. v3 vs. v4 seems like much less of a distinction than choosing between pNFS and no pNFS. Frankly, it never even occurred to me that there wouldn't be a mount option to make this choice. Enabling/disabling the layout driver doesn't fit the existing model of choosing mount behavior, and is a big hammer--it's all or nothing. Anyway, here's a use case: I'm working at an HPC/gas+oil/satellite data site. We have an awesome pNFS server for our big data and I want to access my big data with pNFS. We have another server for homedirs, some big data, and other stuff. Some mounts are fine with pNFS, others are abysmal. So, I want to mount some directories with pNFS, and some without pNFS, on the same client, independent of the server configuration. > > Throwing more and more knobs into the kernel is easy. The > difficult bit > is to figure out which are useful knobs, and that is why I > want real use > cases... > > Trond > > > > ----- "Trond Myklebust" <Trond.Myklebust@xxxxxxxxxx> wrote: > > > > > > > > > > Such a mount option could be useful for dealing with > buggy servers > > > (pnfs-wise) so you > > > > could mount one server with pnfs and another without. > > > > > > You can find ways around that. Just use 2 clients: one with pnfs > > > switched on, and one with it off. > > > > > > I really don't want to introduce mount options upstream > unless they > > > are > > > useful in the long term. One off usefulness does not pass > that test. > > > > > > -- > > > Trond Myklebust > > > Linux NFS client maintainer > > > > > > NetApp > > > Trond.Myklebust@xxxxxxxxxx > > > www.netapp.com > > > > > > -- > > > To unsubscribe from this list: send the line "unsubscribe > linux-nfs" > > > in > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Trond Myklebust > Linux NFS client maintainer > > NetApp > Trond.Myklebust@xxxxxxxxxx > www.netapp.com > > > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
