NFS mount error

Geoffrey Leach geoff at hughes.net
Sun Jan 24 00:44:03 UTC 2010


On 01/23/2010 02:39:44 PM, Sam Sharpe wrote:
> On 23 January 2010 22:17, Craig White <craigwhite at azapple.com> wrote:
> > On Sat, 2010-01-23 at 13:59 -0800, Geoffrey Leach wrote:
> >> I've got a simple network, systems 'A' and 'B' connected via
> wireless.
> >> B wants to mount A's /, /home and /usr/local. The fstab entries 
> are
> >> A:/               /A                nfs       defaults        0 0
> >> A:/home           /A-home           nfs       defaults        0 0
> >> A:/usr/local      /A-ul             nfs       defaults        0 0
> >>
> >> With this, B should do the mounts at boot time, assuming A is on
> line,
> >> which it is.
> >>
> >> The curious thing is that the mount of A:/ works fine. mounts of
> A:/
> >> home and A:/usr/local fail with "mount.nfs: Unknown error 521"
> >>
> >> FWIW, B is running Fedora 10, while A is running up-to-date Fedora
> 12.
> >> This worked find prior to reloading F12 on A. Presumably I've
> missed
> >> something -- any ideas?
> > ----
> > at the point of having A:/ already mounted, the other mounts are
> > redundant and confusing.
> 
> Actually they are not - the directories /A/home and /A/usr/local will
> be blank by default, because they will not be exported with the
> "nohide" option in /etc/exports. Mounting them separately might be
> what the OP perceives is the solution to this.
> 
>        nohide
>               This  option is based on the option of the same name
> provided in
>               IRIX NFS.  Normally, if a server exports two 
> filesystems
> one  of
>               which  is  mounted  on  the  other, then the client 
> will
> have to
>               mount both filesystems explicitly to get access to 
> them.
>  If  it
>               just  mounts  the  parent, it will see an empty
> directory at the
>               place where the other filesystem is mounted.  That
> filesystem is
>               "hidden".
> 
>               Setting  the  nohide  option on a filesystem causes it
> not to be
>               hidden, and an appropriately authorised client will be 
> able  to
>               move  from  the  parent  to that filesystem without
> noticing the
>               change.
> 
>               However, some NFS clients do not cope well with  this 
> situation
>               as,  for  instance, it is then possible for two files 
> in
> the one
>               apparent filesystem to have the same inode number.
> 
>               The nohide option is currently only  effective  on 
> single  host
>               exports.   It  does  not work reliably with netgroup,
> subnet, or
>               wildcard exports.
> 
> The other interesting option in /etc/exports that may be worth
> experimenting with is "crossmnt":
> 
>        crossmnt
>               This option is similar to nohide but it makes  it 
> possible  for
>               clients  to  move  from  the  filesystem marked with
> crossmnt to
>               exported filesystems mounted on it.  Thus when a child 
> filesys-
>               tem  "B" is mounted on a parent "A", setting crossmnt 
> on
> "A" has
>               the same effect as setting "nohide" on B.
> 
Sam,

Thanks for the suggestion. I'll report how well they work out.

Regarding Craig's comment, /home and /usr/local are in seperate 
partitions, so access via / is not possible.





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