[DRBD-user] 8.3.11 on RHEL 5.7 w/ MTU of 9000 fails

Andreas Hofmeister andi at collax.com
Sat Jul 23 21:30:25 CEST 2011

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

On 23.07.2011 06:30, Digimer wrote:
>    Any way to debug this? If it looks like a DRBD bug,

I don't think so. I have DRBD running with jumbo frames on several 
machines and it just work (albeit with 0.8.10).

Check you networking.

Try "ping -c1 -Mdo -s 8192 <other node>", that should tell you if you 
get jumbo frames to the other side or if there is a problem on the IP 

If you get something like "From <other node> icmp_seq=1 Frag needed and 
DF set (mtu = <actual MTU>)", check your devices MTU and check your 
routing as it is actually possible to define a MTU per route.

If you just get no answer or the response is too short, check the specs 
of your network hardware. The supported size for jumbo frames varies 
widely, not just between vendors but also between NIC chips from the 
same vendor. In some cases, even different chips support by the same 
driver differ in the maximum frame size.


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