On 1/18/2020 5:55 AM, Marco Marino wrote:
I cannot enable jumbo frames because client and server are 2 hops away and I cannot modify the network. They use public ips for connection, so I can only reduce MTU server side. Why is there an improvement of reliability when MTU = 1400 in your opinion?
MTU size issues can result in packets that require fragmentation and this breaks, for example, OpenVPN in UDP mode because OpenVPN requires unfragmented UDP packets. This happens when MTU discovery is broken somewhere in between because the encapsulation overhead is not taken into account.
Generally, there will be a way to determine the max packet size. For OpenVPN, the -mssfix flag allows setting the maximum size of an encapsulated packet, so it would be better to leave the interface at its default (auto MTU discovery) and use -mssfix 1400. The default value for -mssfix is 1450, so most likely you could make it a bit higher than 1400.
Il giorno sab 18 gen 2020 alle ore 10:56 Radosław Korzeniewski <rados...@korzeniewski.net <mailto:rados...@korzeniewski.net>> ha scritto:Hello, Thanks for the update. sob., 18 sty 2020 o 09:36 Marco Marino <marino....@gmail.com <mailto:marino....@gmail.com>> napisał(a): It seems that setting MTU = 1400 on the server solves the problem. So, it indeed was a network problem then. :) I'm doing a lot of tests with large backup (150GB, 1.5hours long). I will update this thread if the problem persists. For the best network performance you should raise MTU value up to 9000 ensuring all your network equipment support it and not lower it to less than 1500. I bet you have some kind of network packet encapsulation on your backup path. A firewall or vpn, right? best regards Thank you Il giorno gio 16 gen 2020 alle ore 16:21 Radosław Korzeniewski <rados...@korzeniewski.net <mailto:rados...@korzeniewski.net>> ha scritto: Hello, pon., 13 sty 2020 o 20:44 Marco Marino <marino....@gmail.com <mailto:marino....@gmail.com>> napisał(a): so please don't tell me that the problem is the network It depends. You did not show any logs, so it is a bit hard to judge what is going on your site. Please can you give me some advise? I don't know how to solve nor how to debug this problem. If I launch bacula with maximum debug level I don't see any interesting information related to the problem. Could you please show us your failed job logs? thanks-- Radosław Korzeniewskirados...@korzeniewski.net <mailto:rados...@korzeniewski.net>-- Radosław Korzeniewskirados...@korzeniewski.net <mailto:rados...@korzeniewski.net> _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
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