So, even with a particular user only connecting to one node in the pair, you still see the issue? I'm not seeing that in my setup. I only see it when concurrently connecting the same user to two different nodes in the pair.
Blessings, Rob Archibald CTO, EndFirst LLC [email protected] > On Mar 24, 2017, at 12:50 AM, Wolfgang Hennerbichler <[email protected]> wrote: > > Rob, > > Unfortunately I don’t think the director will solve this problem. I have a > director in front of my setup and it is configured to point every client to > one server. It didn’t change anything in its behavior. > I also have a setup without a director where the clients are only allowed to > talk to one host (DNS entries control this) - same thing. > > Wolfgang > >> On Mar 22, 2017, at 23:58, Rob Archibald <[email protected]> wrote: >> >> Ugh, sorry for the formatting. Not sure what happened when it sent through >> the list. Trying again >> >> Blessings, >> Rob Archibald >> CTO, EndFirst LLC >> [email protected] >> >> >> -----Original Message----- >> From: dovecot [mailto:[email protected]] On Behalf Of Rob Archibald >> Sent: Wednesday, March 22, 2017 3:55 PM >> To: 'Wolfgang Hennerbichler'; [email protected] >> Subject: RE: One way dsync replication with dsync -R >> >> I'm using dsync successfully to keep two nodes synchronized, but I have the >> same problems as you. When I first set it up, I purposely had my phone >> connected to one node and my desktop connected to the other node. This >> allowed me to watch for the very issues you're referring to. I ran into them >> enough that I quit using it that way. But, what I also found was that it was >> just a timing issue. If they weren't synchronized, I could wait a bit and >> they would get synched up. Obviously that doesn't work too great if you're >> sending clients to both nodes through a load balancer though. But, since it >> was just a timing issue, it also made me feel plenty comfortable using 2-way >> sync. I've been able to verify that whichever node is the "master" that the >> other node will be in sync soon thereafter. It just doesn't work great if >> you're logged into both at the same time. >> >> How does that help you may ask? Well, my plan is to setup Dovecot Director >> on each of my node pairs to enable load balancing that way instead of >> through some other load balancer. Director should ensure that all clients of >> a single user will be directed to the same node. Since I haven't set that up >> yet, I can't guarantee it'll work, but based on my testing and reading, I >> think it should be fine. >> >> The benefits I'm expecting are: >> 1. Redundant and reliable storage with data always in 2 places at once >> >> 2. All devices of a single user always go to the same server so that there >> is no risk of synchronization delays between devices >> >> 3. Local storage connections for Dovecot so hopefully a lot fewer index >> corruption issues compared to NFS >> >> 4. Redundant compute nodes so if one server goes down, clients can still >> connect >> >> >> At a high level, my complete setup that I'm building is to 1. Shard users >> into separate server pairs using Dovecot Proxy, 2. Load-balance them within >> the server pair using Dovecot Director. Hopefully my attempt to explain will >> come out well in ASCII: >> >> Server sharding (however many pairs needed to support users. 4 users each >> obviously only for illustration purposes) ========================= >> >> Server pair 1 (servers A & B) Users 1-4 >> >> Server pair 2 (servers C & D) Users 5-8 >> >> User connections >> ============= >> User 1 device 1 ---> Load balancer ---> Dovecot proxy A ---> Send to Server >> A running Director ---> Connect on Server A >> >> User 2 device 1 ---> Load balancer ---> Dovecot proxy B ---> Send to Server >> A running Director ---> Connect on Server B >> >> User 5 device 1 ---> Load balancer ---> Dovecot proxy C ---> Send to Server >> C running Director ---> Connect on Server C >> >> User 1 device 2 ---> Load balancer ---> Dovecot proxy D ---> Send to Server >> A running Director ---> Connect on Server A >> >> User 7 device 1 ---> Load balancer ---> Dovecot proxy A ---> Send to Server >> C running Director ---> Connect on Server D >> >> User 6 device 1 ---> Load balancer ---> Dovecot proxy B ---> Send to Server >> C running Director ---> Connect on Server C >> >> User 3 device 1 ---> Load balancer ---> Dovecot proxy C ---> Send to Server >> A running Director ---> Connect on Server B >> >> User 8 device 1 ---> Load balancer ---> Dovecot proxy D ---> Send to Server >> C running Director ---> Connect on Server D >> >> User 3 device 2 ---> Load balancer ---> Dovecot proxy A ---> Send to Server >> A running Director ---> Connect on Server B >> >> User 5 device 3 ---> Load balancer ---> Dovecot proxy B ---> Send to Server >> C running Director ---> Connect on Server C >> >> User 5 device 2 ---> Load balancer ---> Dovecot proxy C ---> Send to Server >> C running Director ---> Connect on Server C >> >> User 4 device 1 ---> Load balancer ---> Dovecot proxy D ---> Send to Server >> A running Director ---> Connect on Server A >> >> User 5 device 4 ---> Load balancer ---> Dovecot proxy A ---> Send to Server >> C running Director ---> Connect on Server C >> >> User 1 device 3 ---> Load balancer ---> Dovecot proxy B ---> Send to Server >> A running Director ---> Connect on Server A >> >> User 1 device 4 ---> Load balancer ---> Dovecot proxy C ---> Send to Server >> A running Director ---> Connect on Server A >> >> User 6 device 2 ---> Load balancer ---> Dovecot proxy D ---> Send to Server >> C running Director ---> Connect on Server C >> >> User 2 device 2 ---> Load balancer ---> Dovecot proxy A ---> Send to Server >> A running Director ---> Connect on Server B >> >> Results >> =========== >> User 1, 4 - Server A >> User 2, 3 - Server B >> User 5, 6 - Server C >> User 7, 8 - Server D >> >> I would love to hear if others have gotten something like this working. >> >> Blessings, >> Rob Archibald >> CTO, EndFirst LLC >> [email protected] >> >> -----Original Message----- >> From: dovecot [mailto:[email protected]] On Behalf Of Wolfgang >> Hennerbichler >> Sent: Wednesday, March 22, 2017 2:11 PM >> To: [email protected] >> Subject: One way dsync replication with dsync -R >> >> Hi dovecot users, >> >> I’ve found the -R parameter for dsync. Does this enable one-way syncing if >> enabled on the slave in replication_dsync_parameters? The documentation >> doesn’t mention much what happens if I enable this on the “replciation >> slave”. >> >> Before you ask: Two way synchronisation causes issues in my installation >> (see the unanswered thread here: >> http://www.dovecot.org/list/dovecot/2017-March/107431.html), it causes >> unread, deleted messages to re-appear. I would hope that one-way >> synchronisation would avoid this, but I’d also like to know if the -R >> parameter is safe to use. >> I am also still wondering if anybody has a perfectly working >> 2-way-synchronised dovecot installation (and I’m interested in your dovecot >> -n). >> >> wogri
