In a word: Bonding. See Nick Ferrier’s post to Debian-Administration. Grab my check_bonding.pl script from my Subversion respository so you can monitor your links. Get two managed switches (I like the DLink DGS-3324SR gigabit switches). Enable MSTP (Multiple vlan Spanning Tree Protocol) on ports 1, 2, 23 and 24, and disable spanning tree on all other ports; patch ports 23 to 1 on the next switch, and 24 to 2 on the next so you have two links between each switch. Plug your two interfaces into any of the other ports (3-22) on each switch. End of story.
Category: Computing
All I.T. related rants/posts.
UML and NTPL ate my bind, mysql, etc.
So, Running a combination of testing and unstable on my Bytemark UML instance, and over the course of time, the NTPL libraries started to turn up in /lib/tls. Turns out that UML and NTPL are incompatible: every binary I used that utilised threads, such as MySQL, Bind9, Nslookup, all segfault when these libraries are accesible.
Googling around shows that NTPL support doesnt work under UML: the work around is to rename the /lib/tls directory (eg, /lib/tls.disable) so that it can’t be found.
No gallery at the moment
Due to the g++ transition, and me following unstable a little too closely, the Gallery here has gone AWOL. Hopefully the unstable g++ stuff will be completed shortly, and I can sync back up to the latest modperl2.
SATA disks, Debian with 2.4, 2.6 kernels
I was installing a Dell 750 host, which has SATA disks. Using the 2.4.27 kernel with FAI, the disk is seen as /dev/hdc, however when switching to a 2.6 kernel this becomes a SCSI disk as /dev/sda. Update your /etc/fstab and your lilo/grub root device configuration.
Configuring APC Rack PDUs
A brand new APC should be ready to have its IP set via using an ‘arp and ping’ technique. Its in the manual, but worth noting, since I normally google search before RTFM! And so does most of the world..
- On any running host on the same network, set the ARP for the MAC address of the device. Eg:
arp -s 10.0.0.10 00:C0:B7:76:08:CCwill tell the host you are on to send to hat mac address when you use the IP 10.0.0.10. - On the same host, before the arp expires (normally 5 mins), send a ping to this IP with a special size of 113 bytes. Eg:
ping -l 113 10.0.0.10from Win, orping -s 113 10.0.0.10if you have a better operating system (Linux)!
If this fails, then you need to get the serial cable out and wire it up (9600 8N1 is default I think, turn off ALL flow control; no hardware, no software). Password recovery: find the small hole and use a paper clip or similar to reset the device. You have to reset it twice for it to take effect, and then you can use the default username and password of apc/apc.