Troubleshooting guide

• Shuts down the gm_mapper daemon

• ifconfig’s down the myri* ethernet devices

• Unloads the GM module (using rmmod)

The gm "restart" script performs a gm stop followed by a gm start.

Note:

1. GM is not in the critical performance path so it does not need to be built with

specialized compilers and flags. GM should be built with Gnu gcc and only built with

-O level of optimization.

2. GM should be installed in an NFS-mounted area.

3. gm_install_drivers and /etc/init.d/gm start need to be run on all nodes in the

cluster!

4. The kernel header files MUST match the running kernel exactly: not only should they

both be from the same version, but they should also contain the same kernel

configuration options. (Be careful with RedHat kernel packages.)

5. By default, we assume that you have PCIXE, PCIXF, PCIXD, PCI64C, PCI64B, or

PCI64 NICs. (PCI32 NICs are not supported in GM-2.)

6. If a host is rebooted, you must reload the GM-2 driver.

The most common /etc/init.d/gm start failures are:

• APIC IRQ conflicts (encountered on several Tyan and AMD motherboards)

• Running kernel / source kernel mismatch

• AGP (nVidia, ATI) conflicts

• Defective or inadequate riser cards

The solutions for these problems are summarized in the FAQ entry “GM Installation

fails. What does this error message mean?” (http://www.myri.com/cgi-bin/fom?file=46).

Undoubtedly, if you encounter an issue on a specific mother board or version of Linux,

someone else has too, and it will be documented on the Myricom web site. If not, contact

us at help@myri.com.

3. Enabling IP over Myrinet (Ethernet emulation) (OPTIONAL)

If you wish to run IP over Myrinet (ethernet emulation), the Linux command to enable IP

over GM is as follows:

/sbin/ifconfig myri0 <ip_address> up

where you must replace myri0 with the appropriate name (myri1, myri2, etc.) if you have

more than one Myrinet NIC per host.

Note that GM-2 yields better IP performance over Myrinet than GM-1.