From: Robert Towster (robert@towster.com)
Date: Wed Aug 28 2002 - 19:14:13 EDT
We just migrated our netbackup server from a 450 running 2.6 to a 3800
running 8. Several times we have had the network freeze up. Both boxes
were connected via gigabit to two different subnets. On the new box I
have verified that both ethernet cards have different mac addresses. I
have an /etc/notrouter file (and a /etc/defaultrouter). I can ping both
in and out both interfaces.
My best guess right now is that perhaps there is a tcp parameter that I
need to tweak but I do not know what I should look at changing. I have
generated a list of those tcp parameters that are different between the
old server and the new server. Does anyone have any suggestions as to
what parameters I should change on the new server? (and perhaps why I
should change those values..)
Here is the list of the parameters that are not the same on the boxes:
tcp_conn_grace_period - new - 0
tcp_conn_grace_period - old - 500
tcp_cwnd_max - new - 1048576
tcp_cwnd_max - old - 262144
tcp_ip_ttl - old - 255
tcp_ipv4_ttl - new - 64
tcp_mss_min - new - 108
tcp_mss_min - old - 1
tcp_recv_hiwat - new - 24576
tcp_recv_hiwat - old - 32768
tcp_rexmit_interval_extra - new - 0
tcp_rexmit_interval_extra - old - 200
tcp_rtt_updates - new - 20
tcp_rtt_updates - old - 0
tcp_slow_start_after_idle - new - 4
tcp_slow_start_after_idle - old - 2
tcp_slow_start_initial - new - 4
tcp_slow_start_initial - old - 1
tcp_tstamp_if_wscale - new - 1
tcp_tstamp_if_wscale - old - 0
tcp_xmit_hiwat - new - 16384
tcp_xmit_hiwat - old - 32768
tcp_xmit_lowat - new - 4096
tcp_xmit_lowat - old - 24576
If you have any suggestions of what else I should look at please let me
know that also.
TIA
Robert Towster
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