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BL8X0c i2 Flex 10 Jumbo Frames MTU

Occasional Contributor

BL8X0c i2 Flex 10 Jumbo Frames MTU


I am moving my system from Bl860c to BL860c i2.
The MTU for the integrated Network,Jumbo Frames is 9000, however on the New BL860c i2, integrated network port (Flex 10), it appears as 7519. This is causing problems for oracle RAC interconnect, and the DB can't start. error
"ORA-03113: end-of-file on communication channel" If run on the older blade there is no issue. This is a two node cluster. One Older blade an the other the new blade. If two older blade is run there is no issues.
$ tcpip sh inter
Interface IP_Addr Network mask Receive Send MTU

LO0 218 218 4096
WE0 xxx.xxx.5.48 0 0 1500
WE1 xxx.xxx.101.163 0 0 1500
WE2 xxx.xxx.10.163 0 0 7519

HP TCP/IP Services for OpenVMS Industry Standard 64 Version V5.7 - ECO 1
on an HP BL860c i2 (1.73GHz/6.0MB) running OpenVMS V8.4

Thanks for any suggestions.

Frequent Advisor

Re: BL8X0c i2 Flex 10 Jumbo Frames MTU

Jumbo frames on i2 systems are limited to what fits into an 8k page, so 8192 - overhead = 7519. Older blades have map registers that allow the driver to make physically discontiguous buffers appear to be physically contiguous, so the driver can allocate jumbo buffers that cross a page boundary.

I don't have any suggestion other than to look for how to Oracle RAC would deal with other devices that don't have a 9000 byte jumbo frame MTU as well, like some Intel Gigabit devices (which have a similar limitation) and LAN Failover devices (which limit for lowest common denominator).

- Dick