Re: dsync replication
I have a ~2000 user mailcluster on a rbd blockdevice backed by ceph, it’s distributed over ~8 disks and works without any issues for more than 3 years now. Ceph is not so fast as DRBD but more flexible. I would not expect any issues with DRBD, except for the problem that logical failures (e. g. an accidental rm -rf /va/rmail) means your cluster is dead, whereas with dsync nothing is lost. wogri > On Mar 31, 2017, at 16:15, George Dimakopoulos wrote: > > Is it stable for dovecot 2.2.27 to implement DRBD (or HAST) on block level > for maildir data replication instead of using dsync plugin? > > Regards, > > George
dsync replication
Is it stable for dovecot 2.2.27 to implement DRBD (or HAST) on block level for maildir data replication instead of using dsync plugin? Regards, George
Re: Slow performance with large folders over the Internet
On 03/31/2017 12:03 AM, Shawn Heisey wrote: > Dovecot package version is 1:1.2.15-7+deb6u1. It is in Debian 6.0.10, > using the Debian package. > > The server is in my basement at home, and is exposed to the Internet so > I can fully access my mail from anywhere. I use IMAP for reading mail. > > I have a number of folders in my mailbox that have thousands of messages > in them, from mailing lists. > > When I'm at home, I have a LAN connection to the server. It goes > through a Cisco firewall that limits the connection speed to 100Mb/s. > In this situation, I can open a folder with 25000 messages in it, click > on the next unread message that Thunderbird did not know about before, > and within a second or two, the message will download, allowing me to > view it and reply. > > When I'm at work, with highly variable network latency between > Thunderbird and the server, doing exactly the same thing takes a LOT > longer. I have seen it take as long as 15 minutes for a single message. > If I open a folder with only a few messages in it, it is fast. > > The server is not overloaded -- I can log into it with ssh and use "mutt > -f" to open a folder directly. Loading thousands of messages into mutt > takes a while, but I have no difficulty using the ssh connection and > running commandline programs. > > This suggests that the IMAP communication between the server and the > client involves a large amount of back and forth communication when the > message count in the folder is high, possibly something for every > message in the folder. It happens quickly on a LAN but crawls on a > connection with high latency. I can understand it taking a few seconds > longer on a high-latency link, but it takes minutes. > > I do plan on building a new server and migrating to Dovecot 2.x, but I > haven't had the time to work on that. > > Is this a known problem? If so, is it fixed in 2.x? > > Thanks, > Shawn This sounds like your companies firewall trying a mitm attack or similar. Just a wild guess. If the SSH-connection is good (probably ignored by the firewall or maybe even prioritized), then forward your IMAP-traffic through it and see if the problem persists. This is not meant as a solution, but to help analyze the problem. # ssh -L 10993:127.0.0.1:993 you@your.server Then connect with Thunderbird to 127.0.0.1:10993. You could also use :143, the SSH-tunnel is already encrypted. Greetings Daniel signature.asc Description: OpenPGP digital signature
Re: Slow performance with large folders over the Internet
On 03/31/2017 12:03 AM, Shawn Heisey wrote: > Dovecot package version is 1:1.2.15-7+deb6u1. It is in Debian 6.0.10, > using the Debian package. > > The server is in my basement at home, and is exposed to the Internet so > I can fully access my mail from anywhere. I use IMAP for reading mail. > > I have a number of folders in my mailbox that have thousands of messages > in them, from mailing lists. > > When I'm at home, I have a LAN connection to the server. It goes > through a Cisco firewall that limits the connection speed to 100Mb/s. > In this situation, I can open a folder with 25000 messages in it, click > on the next unread message that Thunderbird did not know about before, > and within a second or two, the message will download, allowing me to > view it and reply. > > When I'm at work, with highly variable network latency between > Thunderbird and the server, doing exactly the same thing takes a LOT > longer. I have seen it take as long as 15 minutes for a single message. > If I open a folder with only a few messages in it, it is fast. > > The server is not overloaded -- I can log into it with ssh and use "mutt > -f" to open a folder directly. Loading thousands of messages into mutt > takes a while, but I have no difficulty using the ssh connection and > running commandline programs. > > This suggests that the IMAP communication between the server and the > client involves a large amount of back and forth communication when the > message count in the folder is high, possibly something for every > message in the folder. It happens quickly on a LAN but crawls on a > connection with high latency. I can understand it taking a few seconds > longer on a high-latency link, but it takes minutes. > > I do plan on building a new server and migrating to Dovecot 2.x, but I > haven't had the time to work on that. > > Is this a known problem? If so, is it fixed in 2.x? > > Thanks, > Shawn > Hi Shawn, If you think that imap is the problem, you can do an imap session by hand and see where the problems are: openssl s_client -CApath /path/to/your/certs -connect your.server:143 -starttls imap See fi. http://wiki.linuxquestions.org/wiki/Testing_IMAP_via_telnet But from your mail I would say that you might have networking or firewall issues. So I would be looking for interface errors, missing ping packets, traceroute output and so on. Best, gerard
