Geek projects, tidbits and things I'm working on at the moment…

Last year I had an odd issue when installing CentOS 6.0 on a Supermicro motherboard with an Intel PCIe quad port GB nic using an 82576 chip. I got by the initial kernel panic by using pci=noaer as a kernel option but later encountered really weird kernel panics regarding the Intel nic again which required an additional pcie_aspm=off in my grub file. Pretty odd stuff really since this was a server and I wasn’t worried about managing my power consumption since we’re a small company and I simply want the server to stay on. There’s a number of good articles about ASPM & Linux over on the Phoronix.com website which I found very interesting.

Initial bug report from RHEL: https://bugzilla.redhat.com/show_bug.cgi?id=704758

A number of Kernel parameters one can use at boot time to help troubleshoot things: http://www.kernel.org/doc/Documentation/kernel-parameters.txt

Initial Phoronix News article that got me wondering if Linux’s implementation of ASPM might be my problem: http://www.phoronix.com/scan.php?page=news_item&px=MTAwMjg

I can see how ASPM would be really important to laptop users sure, but when I’m installing a server I don’t need stuff shutting down on me when not in use. (Of course this is different for datacenters!)

I’m currently working on building my own iSCSI SAN w/ SCST & a modified Linux kernel. Things are going pretty well but I needed to also bond out the 5 Gb nics so my VMHosts can maximize their connections. In Linux, you bond out an interface by creating a new network interface and telling the physical nics to register w/ that virtual network interface. There’s also 7 different types of bonding modes but the most common one is mode 6 or balance-ALB (active load balancing.)

If you’re using CentOS or RHEL like I am you cd to /etc/sysconfig/network-scripts/ and vi ifcfg-bond0.

Once you’ve got vi open, you dump the following in (this is an example only. Please change your IPADDR, NETMASK and NETWORK parameters as needed.)

DEVICE=bond0
BOOTPROTO=none
ONBOOT=yes
NETWORK=10.0.0.0
NETMASK=255.255.0.0
IPADDR=10.0.0.100
USERCTL=no

From there, you then modify your individual eth# interface config files so they point to the bonded device. As an example, here’s my /etc/sysconfig/network-scripts/ifcfg-eth0 interface file.

DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no

And oh ya, don’t forget to modify your modprobe.conf file to specify the loading of the bond kernel module and what options it will needed @ run-time.

alias bond0 bonding 
options bond0 mode=6 miimon=100

Couple of useful links. There’s tons of good info on bonding w/ Linux. Keep in mind, some distros don’t want you to modify the individual interface config files so use their administrator control panel first if possible.

http://www.how2centos.com/how-to-set-up-network-bonding-with-centos-5x/
http://www.howtoforge.com/network_card_bonding_centos