[DRBD-user] kernel soft lockup

yvette hirth yvette at dbtgroup.com
Thu Dec 30 20:16:51 CET 2010

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Marco Barbero wrote:

>> I'm exeriencing a nasty kernel soft lockup on one cluster.  Have to
>> say I have tons of clusters using same config and all is working fine

i recently experienced cluster lockup issues because my ethernet 
adapters (4 / server) which were bonded to "bond0" inadvertently had 
some options which "appear to be incompatible" with intra-cluster 
communications, i.e.:

tx-checksumming was on; and
scatter-gather was on; and
TSO was on; and
generic segmentation offload was on.

i noted that these options can cause problems on both bonded and 
non-bonded intf's.  i verified the error using wireshark:  i saw tcp and 
udp checksum errors coming from one server with these options set.

if you do not bond, you can reset these with:

ethtool -K eth"x" tx off sg off tso off gso off

if you bond, you'll probably be unable to reset these with ethtool; 
instead, reset the eth"x" intf's themselves (even tho they are slaves) 
and the bonded intf will reset automagically.  i verified the fix using 
wireshark:  the server with the checksum errors is now behaving nicely.

yvette hirth

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