old nfs client, new nfs host, incorrect mount option?

[Tom Horsley]

I've got a system running centos 7 hosting lots of filesystems
available for NFS mounting.

I've got a gazillion virtual machines that need to have their
fstab edited to mount these filesystems.

I've now discovered that mechanically editing the fstab doesn't
work. On most of the VMs, if I say something like this:

bob:/builder /bob/builder nfs rw,bg,hard,rsize=8192,wsize=8192 0 0

then everything "just works", but as I go back in time, when I get
to a machine running fedora 11, I get the highly informative
"incorrect mount option" message. With lots of experimentation,
I eventually found that I could change the type from "nfs" to "nfs4"
and the mount would work.

Is there a guide somewhere for which idioms to use for which version
of linux I want to mount in? Is there any way to automate adding
these fstab entries correctly? I thought the nfs server was supposed
to automatically fall back to old protocols if the client didn't know
something, am I missing some sort of configuration on the centos 7 host?

[Tom Horsley]

On Fri, 10 Apr 2015 17:18:56 -0700
Rick Stevens wrote:

>  I think just specifying "-t nfs" should make the client
> negotiate with
>  the server and try to get you the latest that the server provides. 
Yea, that worked most everywhere, but on fedora 11 and ubuntu 8.10
(so far) I think there were bugs in nfs-utils. Those systems I had to
manually change to use nfs4 as the type

[Rick Stevens]

On 04/10/2015 04:35 PM, Tom H wrote:
>  On Thu, Apr 9, 2015 at 9:15 AM, Tom Horsley
> <horsley1953(a)gmail.com&gt; wrote:
> >
> > I've got a system running centos 7 hosting lots of filesystems
> > available for NFS mounting.
> >
> > I've got a gazillion virtual machines that need to have their
> > fstab edited to mount these filesystems.
> >
> > I've now discovered that mechanically editing the fstab doesn't
> > work. On most of the VMs, if I say something like this:
> >
> > bob:/builder /bob/builder nfs rw,bg,hard,rsize=8192,wsize=8192 0 0
> >
> > then everything "just works", but as I go back in time, when I get
> > to a machine running fedora 11, I get the highly informative
> > "incorrect mount option" message. With lots of experimentation,
> > I eventually found that I could change the type from "nfs" to
> "nfs4"
> > and the mount would work.
> >
> > Is there a guide somewhere for which idioms to use for which version
> > of linux I want to mount in? Is there any way to automate adding
> > these fstab entries correctly? I thought the nfs server was supposed
> > to automatically fall back to old protocols if the client didn't know
> > something, am I missing some sort of configuration on the centos 7 host?
>
>  Fedora defaulted to nfsv4 with F13 so "mount -t nfs ..." on F11 would
>  default to nfsv3 and you had to use "mount -t nfs4 ..." to mount an
>  nfsv4 share.
>
>  "nfs4" is now deprecated (see "man nfs" on F13 or higher; or perhaps
>  F14 or higher).
>
>  Use "mount -t nfs -o nfsvers=<vers> ..." to specify a version, whether
>  2/3/4, except pre-F13 or pre-F14 (I can't remember which).
>
>  Before the "nfs4" option was deprecated, you specified an nfsv2 or
>  nfsv3 mount with "mount -t nfs -o nfsvers=<vers> ...", an nfsv4 mount
>  with "mount -t nfs4 ...", and you couldn't use "mount -t nfs -o
>  nfsvers=4 ..." for an nfsv4 mount.
>
>  You could use "nfs4" for all of your mounts from F11 to F21, until
>  it's removed, if ever.
>
>  You can check which nfs versions are being used by an nfs server with
>  "cat /proc/fs/nfsd/versions" or "rpcinfo -s" or "rpcinfo
> -p".
>
>  CentOS 7 defaults to nfsv4 but unless you've disabled nfsv3 or are
>  running a firewall and haven't set nfs up to share through it, nfsv3
>  mounts should work. Try "mount -v -t nfs ..." on your F11 box and you
>  might get a more verbose error message (if you're lucky!). 
I think just specifying "-t nfs" should make the client negotiate with
the server and try to get you the latest that the server provides.
You'd use the "nfsvers=" stuff to force it one way or the other. You'd
use "proto=" to force UDP or TCP (UDP default in V3, TCP in V4).
----------------------------------------------------------------------
- Rick Stevens, Systems Engineer, AllDigital    ricks(a)alldigital.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
-                                                                    -
-   "Do you suffer from long-term memory loss?"  "I don't
remember"  -
-                            -- Chumbawumba, "Amnesia" (TubThumping) -
----------------------------------------------------------------------

[Tom H]

On Thu, Apr 9, 2015 at 9:15 AM, Tom Horsley <horsley1953(a)gmail.com&gt; wrote:
>  I've got a system running centos 7 hosting lots of filesystems
>  available for NFS mounting.
>
>  I've got a gazillion virtual machines that need to have their
>  fstab edited to mount these filesystems.
>
>  I've now discovered that mechanically editing the fstab doesn't
>  work. On most of the VMs, if I say something like this:
>
>  bob:/builder /bob/builder nfs rw,bg,hard,rsize=8192,wsize=8192 0 0
>
>  then everything "just works", but as I go back in time, when I get
>  to a machine running fedora 11, I get the highly informative
>  "incorrect mount option" message. With lots of experimentation,
>  I eventually found that I could change the type from "nfs" to "nfs4"
>  and the mount would work.
>
>  Is there a guide somewhere for which idioms to use for which version
>  of linux I want to mount in? Is there any way to automate adding
>  these fstab entries correctly? I thought the nfs server was supposed
>  to automatically fall back to old protocols if the client didn't know
>  something, am I missing some sort of configuration on the centos 7 host? 
Fedora defaulted to nfsv4 with F13 so "mount -t nfs ..." on F11 would
default to nfsv3 and you had to use "mount -t nfs4 ..." to mount an
nfsv4 share.

"nfs4" is now deprecated (see "man nfs" on F13 or higher; or perhaps
F14 or higher).

Use "mount -t nfs -o nfsvers=<vers> ..." to specify a version, whether
2/3/4, except pre-F13 or pre-F14 (I can't remember which).

Before the "nfs4" option was deprecated, you specified an nfsv2 or
nfsv3 mount with "mount -t nfs -o nfsvers=<vers> ...", an nfsv4 mount
with "mount -t nfs4 ...", and you couldn't use "mount -t nfs -o
nfsvers=4 ..." for an nfsv4 mount.

You could use "nfs4" for all of your mounts from F11 to F21, until
it's removed, if ever.

You can check which nfs versions are being used by an nfs server with
"cat /proc/fs/nfsd/versions" or "rpcinfo -s" or "rpcinfo
-p".

CentOS 7 defaults to nfsv4 but unless you've disabled nfsv3 or are
running a firewall and haven't set nfs up to share through it, nfsv3
mounts should work. Try "mount -v -t nfs ..." on your F11 box and you
might get a more verbose error message (if you're lucky!).

[Tom Horsley]

On Thu, 9 Apr 2015 09:48:10 -0700
Rick Stevens wrote:

>  CentOS 7 may default to offering only NFSv4 (ugh!). You can check
> this
>  by doing "rpcinfo -p NFS-server-name-or-IP-address" and looking at the
>  "nfs" lines. The version number that NFS supports will be listed in the
>  "vers" (second) column of the display. 
Thanks, rpcinfo is a new one to add to my list off tricks, but it
does say nfs 3 and 4 is supported. I guess it is just bugs in ancient
versions of the nfs-utils on some of the old systems. I know when
I was trying to mount fielsystems from really old hosts, I had
the opposite problem. Some systems had to say nfsvers=3 and others
wouldn't work with that, but would work with proto=udp.

[Rick Stevens]

On 04/09/2015 06:15 AM, Tom Horsley wrote:
>  I've got a system running centos 7 hosting lots of filesystems
>  available for NFS mounting.
>
>  I've got a gazillion virtual machines that need to have their
>  fstab edited to mount these filesystems.
>
>  I've now discovered that mechanically editing the fstab doesn't
>  work. On most of the VMs, if I say something like this:
>
>  bob:/builder /bob/builder nfs rw,bg,hard,rsize=8192,wsize=8192 0 0
>
>  then everything "just works", but as I go back in time, when I get
>  to a machine running fedora 11, I get the highly informative
>  "incorrect mount option" message. With lots of experimentation,
>  I eventually found that I could change the type from "nfs" to "nfs4"
>  and the mount would work.
>
>  Is there a guide somewhere for which idioms to use for which version
>  of linux I want to mount in? Is there any way to automate adding
>  these fstab entries correctly? I thought the nfs server was supposed
>  to automatically fall back to old protocols if the client didn't know
>  something, am I missing some sort of configuration on the centos 7 host? 
The older "nfs" thing generally means NFSv3 or later, but I think it
prefers NFSv3. Specifying "nfs4" means NFSv4 and newer only. This can
also be done via using "nfs" as the filesystem type, but adding
"nfsvers=4" in the options for the mount (e.g. "rw,hard,nfsvers=4").

CentOS 7 may default to offering only NFSv4 (ugh!). You can check this
by doing "rpcinfo -p NFS-server-name-or-IP-address" and looking at the
"nfs" lines. The version number that NFS supports will be listed in the
"vers" (second) column of the display.
----------------------------------------------------------------------
- Rick Stevens, Systems Engineer, AllDigital    ricks(a)alldigital.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
-                                                                    -
-   Let us think the unthinkable. Let us do the undoable. Let us     -
-   prepare to grapple with the ineffable itself, and see if we may  -
-                      not eff it up after all.                      -
-                                                 -- Douglas Adams   -
----------------------------------------------------------------------

[Tom H]

On Fri, Apr 10, 2015 at 8:18 PM, Rick Stevens <ricks(a)alldigital.com&gt; wrote:
>  On 04/10/2015 04:35 PM, Tom H wrote:
> > On Thu, Apr 9, 2015 at 9:15 AM, Tom Horsley <horsley1953(a)gmail.com&gt; wrote:
> >
> > You could use "nfs4" for all of your mounts from F11 to F21, until
> > it's removed, if ever.
> >
> > You can check which nfs versions are being used by an nfs server with
> > "cat /proc/fs/nfsd/versions" or "rpcinfo -s" or "rpcinfo
> -p".
> >
> > CentOS 7 defaults to nfsv4 but unless you've disabled nfsv3 or are
> > running a firewall and haven't set nfs up to share through it, nfsv3
> > mounts should work. Try "mount -v -t nfs ..." on your F11 box and you
> > might get a more verbose error message (if you're lucky!).
>
>  I think just specifying "-t nfs" should make the client negotiate with
>  the server and try to get you the latest that the server provides.
>  You'd use the "nfsvers=" stuff to force it one way or the other. You'd
>  use "proto=" to force UDP or TCP (UDP default in V3, TCP in V4). 
But the other Tom H said that "-t nfs" was failing when mounting a
CentOS 7 share from an F11 system...