[Dovecot] dovecot-uidlist crashing and re retriving messages by pop3 clients

[Piotr Rotter]

Hello,

I have issue with dovecot (v. 2.1.13)configuration after implementation 
dovecot-lda (I used maildrop earlier). Now i have 9 servers with storage 
by NFS v3. My problem is frequently dovecot-uidlist crashing.

2013-02-13T13:34:02.447969+01:00 k1 dovecot: imap(user at domain.com): 
Error: Broken file /path_to_mailbox/dovecot-uidlist line 3170: Invalid 
data:
2013-02-13T13:34:34.527715+01:00 k1 dovecot: pop3(user at domain.com): 
Error: Broken file /path_to_mailbox/dovecot-uidlist line 367: Invalid 
data:

It happens few time in minute for diferent users and has effect to re 
retriving messages by pop3 clients.

This my NFS mount options: (rw,tcp,vers=3,actimeo=0)

10-mail.conf options:
mmap_disable = yes
dotlock_use_excl = yes
mail_fsync=always
mail_nfs_storage = yes
mail_nfs_index = yes
lock_method = dotlock

I do not know what I did wrong and how solve this issue. Maybe NFS v4 or 
fcntl locks or migration to pop3_uidl_format = %g will by solution. 
Please some hint.

Please any help for solve this issue and sorry my english.