2008-01-10 19:57:01

by Jeff Garzik

[permalink] [raw]
Subject: Turning off delegations in NFSv4 server?

Besides hacking the code, is there an easy way to turn off NFSv4
delegations in the kernel v4 server?

I'd like to observe behavior of the Linux v4 client when delegations are
not available.

Thanks,

Jeff


2008-01-10 20:00:34

by [email protected]

[permalink] [raw]
Subject: Re: Turning off delegations in NFSv4 server?

On Thu, Jan 10, 2008 at 02:57:01PM -0500, Jeff Garzik wrote:
> Besides hacking the code, is there an easy way to turn off NFSv4
> delegations in the kernel v4 server?
>
> I'd like to observe behavior of the Linux v4 client when delegations are
> not available.

The easiest thing is probably just to turn off leases:

echo 0 >/proc/sys/fs/leases-enable

--b.

2010-03-04 14:33:18

by [email protected]

[permalink] [raw]
Subject: Re: Turning off delegations in NFSv4 server?

On Thu, Mar 04, 2010 at 09:23:26AM +0000, Matt Bernstein wrote:
> On Jan 10 2008 J. Bruce Fields wrote:
>> On Thu, Jan 10, 2008 at 02:57:01PM -0500, Jeff Garzik wrote:
>>> Besides hacking the code, is there an easy way to turn off NFSv4
>>> delegations in the kernel v4 server?
>>>
>>> I'd like to observe behavior of the Linux v4 client when delegations are
>>> not available.
>>
>> The easiest thing is probably just to turn off leases:
>> echo 0 >/proc/sys/fs/leases-enable
>
> I found this from two years ago, and am wondering
> - is this still the easiest thing to do?
> - is this on server, client or both?
> - will it break anything else?
>
> We have a CentOS 5.4 NFS3/NFS4/samba server with about 300 clients on its
> subnet, and another 100-200 on another subnet, which under high load has
> started kernel-panicking (sometimes in nfsd4_cb_recall).

Have you filed a bug with the backtraces?

> I want to disable delegations to see if that cures our symptoms--but I
> worry that turning leases off might cause other problems.

No, it shouldn't cause problems, at least for NFSv4 clients. (Samba may
be more reliant on leases, especially if Samba and NFSv4 clients are
acting on the same files at the same time--but I don't know.)

--b.

>
> For now I'll probably do it anyway, given that status quo isn't stable :(
>
> Matt
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2010-03-04 09:23:26

by Matt Bernstein

[permalink] [raw]
Subject: Re: Turning off delegations in NFSv4 server?

On Jan 10 2008 J. Bruce Fields wrote:
> On Thu, Jan 10, 2008 at 02:57:01PM -0500, Jeff Garzik wrote:
>> Besides hacking the code, is there an easy way to turn off NFSv4
>> delegations in the kernel v4 server?
>>
>> I'd like to observe behavior of the Linux v4 client when delegations are
>> not available.
>
> The easiest thing is probably just to turn off leases:
> echo 0 >/proc/sys/fs/leases-enable

I found this from two years ago, and am wondering
- is this still the easiest thing to do?
- is this on server, client or both?
- will it break anything else?

We have a CentOS 5.4 NFS3/NFS4/samba server with about 300 clients on its
subnet, and another 100-200 on another subnet, which under high load has
started kernel-panicking (sometimes in nfsd4_cb_recall).

I want to disable delegations to see if that cures our symptoms--but I
worry that turning leases off might cause other problems.

For now I'll probably do it anyway, given that status quo isn't stable :(

Matt
_______________________________________________
NFSv4 mailing list
[email protected]
http://linux-nfs.org/cgi-bin/mailman/listinfo/nfsv4

2010-03-05 15:12:48

by Matt Bernstein

[permalink] [raw]
Subject: Re: Turning off delegations in NFSv4 server?

On Mar 4 J. Bruce Fields wrote:
> On Thu, Mar 04, 2010 at 09:23:26AM +0000, Matt Bernstein wrote:
>> On Jan 10 2008 J. Bruce Fields wrote:
>>> The easiest thing is probably just to turn off leases:
>>> echo 0 >/proc/sys/fs/leases-enable
>>
>> I found this from two years ago, and am wondering
>> - is this still the easiest thing to do?
>> - is this on server, client or both?
>> - will it break anything else?
>>
>> We have a CentOS 5.4 NFS3/NFS4/samba server with about 300 clients on its
>> subnet, and another 100-200 on another subnet, which under high load has
>> started kernel-panicking (sometimes in nfsd4_cb_recall).
>
> Have you filed a bug with the backtraces?

Duly nudged. I've posted the most recent one to
<http://bugs.centos.org/view.php?id=4229>.

>> I want to disable delegations to see if that cures our symptoms--but I
>> worry that turning leases off might cause other problems.
>
> No, it shouldn't cause problems, at least for NFSv4 clients. (Samba may
> be more reliant on leases, especially if Samba and NFSv4 clients are
> acting on the same files at the same time--but I don't know.)

Thanks; no-one's grumbled just yet.

Matt

2010-03-05 15:30:30

by [email protected]

[permalink] [raw]
Subject: Re: Turning off delegations in NFSv4 server?

On Fri, Mar 05, 2010 at 03:12:46PM +0000, Matt Bernstein wrote:
> On Mar 4 J. Bruce Fields wrote:
>> On Thu, Mar 04, 2010 at 09:23:26AM +0000, Matt Bernstein wrote:
>>> On Jan 10 2008 J. Bruce Fields wrote:
>>>> The easiest thing is probably just to turn off leases:
>>>> echo 0 >/proc/sys/fs/leases-enable
>>>
>>> I found this from two years ago, and am wondering
>>> - is this still the easiest thing to do?
>>> - is this on server, client or both?
>>> - will it break anything else?
>>>
>>> We have a CentOS 5.4 NFS3/NFS4/samba server with about 300 clients on its
>>> subnet, and another 100-200 on another subnet, which under high load has
>>> started kernel-panicking (sometimes in nfsd4_cb_recall).
>>
>> Have you filed a bug with the backtraces?
>
> Duly nudged. I've posted the most recent one to
> <http://bugs.centos.org/view.php?id=4229>.

OK, thanks. Unfortunately that code has changed quite a bit since
2.6.18. I don't recall this specific bug, but I wouldn't be suprised if
it's something we've since fixed. Looking through 'gitk v2.6.18..
fs/nfsd/nfs4callback.c fs/nfsd/nfs4state.c' for delegation/callback
fixes might be one approach.

--b.

>
>>> I want to disable delegations to see if that cures our symptoms--but I
>>> worry that turning leases off might cause other problems.
>>
>> No, it shouldn't cause problems, at least for NFSv4 clients. (Samba may
>> be more reliant on leases, especially if Samba and NFSv4 clients are
>> acting on the same files at the same time--but I don't know.)
>
> Thanks; no-one's grumbled just yet.
>
> Matt