huge increase in storage activity afther dovecot upgrade

Adi Pircalabu adi at
Thu Nov 15 23:42:45 EET 2018

On 2018-11-16 07:24, Adrian Minta wrote:
> Yes, multiple imap servers using one shared nfs storage. With the same
> config on 2.2.13 the public interface traffic was similar to the
> storage interface, around 100 mbps.
> After we switch to 2.2.27 the storage interface traffic jumped 10
> times while the public interface stayed the same. This make us
> thinking that something is wrong and each time a user logs in the
> whole Inbox content is read by dovecot.
> What you are suggesting goes against the documentations and it may not
> be save, but I will give a  thought.

I was expecting you have multiple IMAP servers using the same shared NFS 
storage, however my question was: are the *individual mailboxes* on that 
share accessed *at the same time* from more than one IMAP server?

Adi Pircalabu

> On 11/15/18 6:23 AM, Adi Pircalabu wrote:
>> Are you connecting to the same mailbox over NFS from multiple IMAP 
>> servers? If not and, at any given time, any mailbox will be accessed 
>> from a single NFS client, try to "dupe" Dovecot into thinking it's not 
>> using NFS. We're running quite successfully such setup with NFSv3 over 
>> TCP, which turned out to be the fastest and most reliable throughout 
>> the years. Here are the mount options:
>> rw,noatime,nodiratime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,nordirplus,proto=tcp,timeo=600,retrans=2,sec=sys,mountvers=3,mountport=1892,mountproto=tcp,local_lock=none 
>> On the Dovecot side we're running with:
>> lock_method = dotlock
>> mail_fsync = never
>> mail_nfs_index = no
>> mail_nfs_storage = no
>> maildir_very_dirty_syncs = yes
>> mmap_disable = yes
>> protocol lda {
>>   mail_fsync = optimized
>> }
>> protocol lmtp {
>>   mail_fsync = optimized
>> }
>> Note: we're using Maildir and the usual "works for me(c), may not work 
>> for everyone" applies.

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