2008-05-16 12:24:13

by Chris Fanning

[permalink] [raw]
Subject: [NFS] async vs. sync. corrupted fs

Hello all,

Could someone help me out?

I'm exporting a whole partition to a client.
Using (rw,no_root_squash,sync, no_subtree_check), when I shutdown the
server _before_ the client, the filesystem on the partion becomes
corrupted.
When I user async, it doesn't happen.

Is this normal?
The exports manpage suggests that 'sync' is the better option.

Thanks.
Chris.

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2008-05-20 08:00:45

by Chris Fanning

[permalink] [raw]
Subject: Re: [NFS] async vs. sync. corrupted fs

On Mon, May 19, 2008 at 4:54 PM, J. Bruce Fields <[email protected]> wrote:
> On Fri, May 16, 2008 at 12:55:59PM +0200, Chris Fanning wrote:
>> Hello all,
>>
>> Could someone help me out?
>>
>> I'm exporting a whole partition to a client.
>> Using (rw,no_root_squash,sync, no_subtree_check), when I shutdown the
>> server _before_ the client, the filesystem on the partion becomes
>> corrupted.
>
> How do you know it becomes corrupted?
>
when I boot the server it reports the partition as corrupted and I
need to perform an fsck.

>> When I user async, it doesn't happen.
>
> "async" the client-side mount option, or "async" the server-side export
> option?
server export.
(rw,no_root_squash,sync, no_subtree_check)

client mount (fstab)
nfs_home_server:/home /home nfs tcp,rw 0 0

>
>> Is this normal?
>
> No.
I didn't think so ;)

Perhaps I can shed some more light on this. The client is diskless.
The problems I'm reporting are with it's /home mount. It's root
filessystem is also a nfs mount (but that is exported form a
_different_ nfs server).
I modify the nfsroot using chroot on the server.

I *think* this might be because of /proc mounted in the chroot get
exported to the client? Any insight?

I've been trying all sorts of combinations yesterday (/proc mounted
and not mounted in the chroot) and I haven't been able to reproduce
the error. Strange becuase it definitely happened when was shutting
down the nfs_home_server while everything else was up and running.

Perahps it is also worth noting that I'm booting the client with
live-initramfs. /home gets mounted after the real
filesystem(aufs,nfs+ram) comes up.
Once the client has booted I can use /home. But it doesn't show up
using 'df', and it is not present in /etc/mtab
However it does show up in /proc/mounts
nfs_home_server:/home /home nfs
rw,vers=3,rsize=32768,wsize=23768,hard,nointr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=192.168.2.2
0 0

Sorry for the convulated reply.
Thanks.
Chris.

>
>> The exports manpage suggests that 'sync' is the better option.
>
> Yes.
>
> --b.
>

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2008-05-19 15:01:59

by [email protected]

[permalink] [raw]
Subject: Re: [NFS] async vs. sync. corrupted fs

On Fri, May 16, 2008 at 12:55:59PM +0200, Chris Fanning wrote:
> Hello all,
>
> Could someone help me out?
>
> I'm exporting a whole partition to a client.
> Using (rw,no_root_squash,sync, no_subtree_check), when I shutdown the
> server _before_ the client, the filesystem on the partion becomes
> corrupted.

How do you know it becomes corrupted?

> When I user async, it doesn't happen.

"async" the client-side mount option, or "async" the server-side export
option?

> Is this normal?

No.

> The exports manpage suggests that 'sync' is the better option.

Yes.

--b.

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