Amdump fails to backup large DLEs

Issue

amdump fails to backup large DLEs. It fails with "Connection reset by peer" error message

Configuration

iptables (firewall packet filter) is configured on the Amanda client

Cause

iptables was breaking the TCP connections that was set up between the Amanda client and server for transferring the error output of the backup command because it was idle. During backup of a large DLE, the message connection can remain idle for a long time.

Solution

Increase tcp keepalive probes:

echo 90 > /proc/sys/net/ipv4/tcp_keepalive_time

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