hang problem when umount a nfs point

hang problem when umount a nfs point

[dahai_tian]

Hi all:
        I mount a local directory to a nfs server. When nfs server is
stopped
for some accidental cause, I try to umount the mount point, the umount
command will hang and 'time out' messages are continually printed in the
terminal. How can I avoid hanging in this case? BTW, This issue does not
exist when I changed nfs version from 4 to 3. 
        Look forward to your response, thanks!

Re: hang problem when umount a nfs point

[Jack Wang]

Hi all,

Anyone who can kindly give some suggestion? or we just put question to
the wrong list?

Thanks.

Jack

2012/11/1 dahai_tian <dahai_tian@usish.com>:
> Hi all:
>         I mount a local directory to a nfs server. When nfs server is
> stopped
> for some accidental cause, I try to umount the mount point, the umount
> command will hang and 'time out' messages are continually printed in the
> terminal. How can I avoid hanging in this case? BTW, This issue does not
> exist when I changed nfs version from 4 to 3.
>         Look forward to your response, thanks!
>
> --
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Re: hang problem when umount a nfs point

[Jack Wang]

2012/11/7 Martín Cigorraga <msx@archlinux.us>:
> On Mon, Nov 5, 2012 at 10:27 PM, Jack Wang <jack.wang.usish@gmail.com>
> wrote:
>>
>> Hi all,
>>
>> Anyone who can kindly give some suggestion? or we just put question to
>> the wrong list?
>>
>> Thanks.
>>
>> Jack
>>
>> 2012/11/1 dahai_tian <dahai_tian@usish.com>:
>> > Hi all:
>> >         I mount a local directory to a nfs server. When nfs server is
>> > stopped
>> > for some accidental cause, I try to umount the mount point, the umount
>> > command will hang and 'time out' messages are continually printed in the
>> > terminal. How can I avoid hanging in this case? BTW, This issue does not
>> > exist when I changed nfs version from 4 to 3.
>> >         Look forward to your response, thanks!

>
> Hi Jack, use the -l (lazy) switch:
> # umount -l {your mounted nfs share}
>
> Also, I wouldn't recommend 'just to kill' the NFS proces(ses) as it (them)
> may leave shared memory a mess.
> (And I would like to see how do you make to mount any NFS share again
> without booting)

Thanks Martin for kindly help.

umount -l did work, but why nfsv3 do not have this problem?

Jack

Re: hang problem when umount a nfs point

[J. Bruce Fields]

On Wed, Nov 07, 2012 at 09:05:51AM +0800, Jack Wang wrote:
> 2012/11/7 Martín Cigorraga <msx@archlinux.us>:
> > On Mon, Nov 5, 2012 at 10:27 PM, Jack Wang <jack.wang.usish@gmail.com>
> > wrote:
> >>
> >> Hi all,
> >>
> >> Anyone who can kindly give some suggestion? or we just put question to
> >> the wrong list?
> >>
> >> Thanks.
> >>
> >> Jack
> >>
> >> 2012/11/1 dahai_tian <dahai_tian@usish.com>:
> >> > Hi all:
> >> >         I mount a local directory to a nfs server. When nfs server is
> >> > stopped
> >> > for some accidental cause, I try to umount the mount point, the umount
> >> > command will hang and 'time out' messages are continually printed in the
> >> > terminal. How can I avoid hanging in this case? BTW, This issue does not
> >> > exist when I changed nfs version from 4 to 3.
> >> >         Look forward to your response, thanks!
> 
> >
> > Hi Jack, use the -l (lazy) switch:
> > # umount -l {your mounted nfs share}
> >
> > Also, I wouldn't recommend 'just to kill' the NFS proces(ses) as it (them)
> > may leave shared memory a mess.
> > (And I would like to see how do you make to mount any NFS share again
> > without booting)
> 
> Thanks Martin for kindly help.
> 
> umount -l did work, but why nfsv3 do not have this problem?

I don't know what it is exactly.  But in general I wouldn't expect
umount to work when the server's unavailable.

--b.

Re: hang problem when umount a nfs point

[Jack Wang]

2012/11/8 J. Bruce Fields <bfields@fieldses.org>:
> On Wed, Nov 07, 2012 at 09:05:51AM +0800, Jack Wang wrote:
>> 2012/11/7 Martín Cigorraga <msx@archlinux.us>:
>> > On Mon, Nov 5, 2012 at 10:27 PM, Jack Wang <jack.wang.usish@gmail.com>
>> > wrote:
>> >>
>> >> Hi all,
>> >>
>> >> Anyone who can kindly give some suggestion? or we just put question to
>> >> the wrong list?
>> >>
>> >> Thanks.
>> >>
>> >> Jack
>> >>
>> >> 2012/11/1 dahai_tian <dahai_tian@usish.com>:
>> >> > Hi all:
>> >> >         I mount a local directory to a nfs server. When nfs server is
>> >> > stopped
>> >> > for some accidental cause, I try to umount the mount point, the umount
>> >> > command will hang and 'time out' messages are continually printed in the
>> >> > terminal. How can I avoid hanging in this case? BTW, This issue does not
>> >> > exist when I changed nfs version from 4 to 3.
>> >> >         Look forward to your response, thanks!
>>
>> >
>> > Hi Jack, use the -l (lazy) switch:
>> > # umount -l {your mounted nfs share}
>> >
>> > Also, I wouldn't recommend 'just to kill' the NFS proces(ses) as it (them)
>> > may leave shared memory a mess.
>> > (And I would like to see how do you make to mount any NFS share again
>> > without booting)
>>
>> Thanks Martin for kindly help.
>>
>> umount -l did work, but why nfsv3 do not have this problem?
>
> I don't know what it is exactly.  But in general I wouldn't expect
> umount to work when the server's unavailable.
>
> --b.

Thanks for your time Bruce, but there are chance the server
unavailable , why you think umount don't work is expected?

Jack

Re: hang problem when umount a nfs point

[J. Bruce Fields]

On Thu, Nov 08, 2012 at 11:03:22AM +0800, Jack Wang wrote:
> 2012/11/8 J. Bruce Fields <bfields@fieldses.org>:
> > On Wed, Nov 07, 2012 at 09:05:51AM +0800, Jack Wang wrote:
> >> 2012/11/7 Martín Cigorraga <msx@archlinux.us>:
> >> > On Mon, Nov 5, 2012 at 10:27 PM, Jack Wang <jack.wang.usish@gmail.com>
> >> > wrote:
> >> >>
> >> >> Hi all,
> >> >>
> >> >> Anyone who can kindly give some suggestion? or we just put question to
> >> >> the wrong list?
> >> >>
> >> >> Thanks.
> >> >>
> >> >> Jack
> >> >>
> >> >> 2012/11/1 dahai_tian <dahai_tian@usish.com>:
> >> >> > Hi all:
> >> >> >         I mount a local directory to a nfs server. When nfs server is
> >> >> > stopped
> >> >> > for some accidental cause, I try to umount the mount point, the umount
> >> >> > command will hang and 'time out' messages are continually printed in the
> >> >> > terminal. How can I avoid hanging in this case? BTW, This issue does not
> >> >> > exist when I changed nfs version from 4 to 3.
> >> >> >         Look forward to your response, thanks!
> >>
> >> >
> >> > Hi Jack, use the -l (lazy) switch:
> >> > # umount -l {your mounted nfs share}
> >> >
> >> > Also, I wouldn't recommend 'just to kill' the NFS proces(ses) as it (them)
> >> > may leave shared memory a mess.
> >> > (And I would like to see how do you make to mount any NFS share again
> >> > without booting)
> >>
> >> Thanks Martin for kindly help.
> >>
> >> umount -l did work, but why nfsv3 do not have this problem?
> >
> > I don't know what it is exactly.  But in general I wouldn't expect
> > umount to work when the server's unavailable.
> >
> > --b.
> 
> Thanks for your time Bruce, but there are chance the server
> unavailable , why you think umount don't work is expected?

It's tough for the client to deal safely with an unreachable server.
Worst case it may still have data in its buffers that applications have
written but that hasn't yet made it to the server.

If you don't have any opens or other state on the filesystem any more,
there might be things that could be done to make it easier to umount in
that case--I haven't thought it through--but I doubt that's a high
priority, so it's likely up to you to write the code and persuade people
it's worthwhile.

--b.

Re: hang problem when umount a nfs point

[Jack Wang]

2012/11/8 J. Bruce Fields <bfields@fieldses.org>:
> On Thu, Nov 08, 2012 at 11:03:22AM +0800, Jack Wang wrote:
>> 2012/11/8 J. Bruce Fields <bfields@fieldses.org>:
>> > On Wed, Nov 07, 2012 at 09:05:51AM +0800, Jack Wang wrote:
>> >> 2012/11/7 Martín Cigorraga <msx@archlinux.us>:
>> >> > On Mon, Nov 5, 2012 at 10:27 PM, Jack Wang <jack.wang.usish@gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Hi all,
>> >> >>
>> >> >> Anyone who can kindly give some suggestion? or we just put question to
>> >> >> the wrong list?
>> >> >>
>> >> >> Thanks.
>> >> >>
>> >> >> Jack
>> >> >>
>> >> >> 2012/11/1 dahai_tian <dahai_tian@usish.com>:
>> >> >> > Hi all:
>> >> >> >         I mount a local directory to a nfs server. When nfs server is
>> >> >> > stopped
>> >> >> > for some accidental cause, I try to umount the mount point, the umount
>> >> >> > command will hang and 'time out' messages are continually printed in the
>> >> >> > terminal. How can I avoid hanging in this case? BTW, This issue does not
>> >> >> > exist when I changed nfs version from 4 to 3.
>> >> >> >         Look forward to your response, thanks!
>> >>
>> >> >
>> >> > Hi Jack, use the -l (lazy) switch:
>> >> > # umount -l {your mounted nfs share}
>> >> >
>> >> > Also, I wouldn't recommend 'just to kill' the NFS proces(ses) as it (them)
>> >> > may leave shared memory a mess.
>> >> > (And I would like to see how do you make to mount any NFS share again
>> >> > without booting)
>> >>
>> >> Thanks Martin for kindly help.
>> >>
>> >> umount -l did work, but why nfsv3 do not have this problem?
>> >
>> > I don't know what it is exactly.  But in general I wouldn't expect
>> > umount to work when the server's unavailable.
>> >
>> > --b.
>>
>> Thanks for your time Bruce, but there are chance the server
>> unavailable , why you think umount don't work is expected?
>
> It's tough for the client to deal safely with an unreachable server.
> Worst case it may still have data in its buffers that applications have
> written but that hasn't yet made it to the server.
>
> If you don't have any opens or other state on the filesystem any more,
> there might be things that could be done to make it easier to umount in
> that case--I haven't thought it through--but I doubt that's a high
> priority, so it's likely up to you to write the code and persuade people
> it's worthwhile.
>
> --b.
Thanks for explaination.

Jack