dovecot and broken uidlist

[Alessio Cecchi]

Hi Claudio,

I made a test with NFS mount with nfsvers=4.1 and CentOS 7 as NFS client 
(our Netapp already have NFS 4.1 enabled) but the problem is still present.

More, I don't like to switch to NFS 4 because is statefull, NFS v3 is 
stateless and for example during maintanace or upgrade of NFS server 
clients haven't problems, the reboot of Netapp is trasparent.

I don't think the problem is related to Netapp, I see the same error in 
a setup of a customer based on Google Cloud (Ubuntu as Dovecot and NFS 
client and Google Cloud NFS volume as storage).

In my case I'm using LDA for local delivery of emails so I hope that 
swithcing to LMTP I will resolve the issue but I'm not use since others 
users said that they are aready using LMTP.

I don't know why on old Linux distro works and recents distro have the 
issue ...

Il 19/01/21 20:21, Claudio Cuqui ha scritto:
> It's a long shot......but I would try to use nfsvers=4.1 in the nfs 
> mount option (instead of nfsvers=3)  - if your netapp supports it - 
> with a newer kernel - 4.14-stable or 4.19-stable (if possible). The 
> reason for that, is a nasty bug found in linux nfs client with older 
> kernels...
>
> https://about.gitlab.com/blog/2018/11/14/how-we-spent-two-weeks-hunting-an-nfs-bug/
>
> Hope this helps...
>
> Regards,
>
> Claudio
>
>
> Em qua., 13 de jan. de 2021 às 12:18, Maciej Milaszewski 
> <maciej.milaszewski at iq.pl <mailto:maciej.milaszewski at iq.pl>> escreveu:
>
>     Hi
>     I have been trying resolve my problem with dovecot for a few days
>     and I
>     dont have idea....
>
>     My environment is: dovecot director+5 dovecot guest
>
>     dovecot-2.2.36.4 from source
>     Linux 3.16.0-11-amd64
>     storage via nfs (NetApp)
>
>     all works fine but when I update OS from debian 8 (kernel 3.16.x) to
>     debian 9 (kernel 4.9.x ) sometimes I get random in logs:
>     Broken dovecot-uidlist
>
>     examle:
>     Error: Broken file
>     /vmail2/po/pollygraf.xxx_pg_pollygraf/Maildir/dovecot-uidlist line 88:
>     Invalid data:
>
>     (for random users - sometimes 10 error in day per node, some times
>     more)
>
>     File looks ok
>
>     But if I change kernel to 3.16.x problem with "Broken file
>     dovecot-uidlist"  - not exists
>     if turn to 4.9 or 5.x - problem exists
>
>     I have storage via nfs with opions:
>     rw,sec=sys,noexec,noatime,tcp,hard,rsize=65536,wsize=65536,intr,nordirplus,nfsvers=3,tcp,actimeo=120
>     I tested with "nocto" or without "nocto" - nothing changes ......
>
>     nfs options in node:
>     mmap_disable = yes
>     mail_fsync = always
>
>     I bet the configuration is correct and I wonder why the problem occurs
>     with other kernels
>     3.x.x - ok
>     4.x - not ok
>
>     I check and user who have problem did not connect to another node in
>     this time
>
>     I dont have idea why problem exists on the kernel 4.x but not in 3.x
>
>
-- 
Alessio Cecchi
Postmaster @ http://www.qboxmail.it
https://www.linkedin.com/in/alessice

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