Udev Question

[C M Reinehr]

On Sat 19 June 2010 03:58:23 pm Lonni J Friedman wrote:
> I'm not sure of the why, but this is how udev works.  It keeps a
> record of every piece of HW.  I've seen this very same behavior when
> swapping hard disks between systems, and I usually need to either hack
> udev's database to reset back to eth0, or just reconfigure the network
> settings to work from the new ethernet numbering assignments.

	Ok, that makes sense. Now that things are quiet and with your clue I made a 
serious effort to find the database & found /dev/.udev/db. After a quick 
look, I think I may just live with it. (I wonder what would happen if I just 
clobbered the whole directory? Do you suppose that udev might just rebuild 
it? I think I'll save that exercise for another day & a test PC instead of 
one of my servers!)

Thanks!

Mike Reinehr

> On Sat, Jun 19, 2010 at 12:53 PM, C M Reinehr <cmr at amsent.com> wrote:
> > Thursday what should have been a relatively simple problem became much
> > more interesting owing the udev system.
> >
> > I have two identical servers -- identical hardware & running exactly the
> > same version of Debian Linux (Lenny) with almost identical software (same
> > system software but different applications).
> >
> > Both use a Tyan Thunder motherboard which came with three ethernet ports:
> > two Broadcom gigabit Ethernet ports plus one Intel 10/100 Ethernet port.
> > For five years, when booting, the system (udev?) would discover first one
> > of the Broadcom ports and name it eth0, then the Intel port as eth1 &
> > finally the remaining Broadcom port as eth2. My /etc/network/interfaces
> > file was configured accordingly to assign static IP numbers and set up
> > routes (copy below) per their MAC numbers.
> >
> > Thursday, while performing some minor software maintenance I rebooted one
> > of the servers -- running my accounting software -- or, at least,
> > attempted to reboot one of the servers. It wouldn't boot. The lights &
> > fans powered up but no POST screen. This was a critical server: no
> > accounting software, no sales order entry, no sales, no money, etc.
> >
> > After fooling with that for a while and deciding that the system was down
> > for the count (probably with a failing power supply) I decided the
> > simplest & fasted way of recovering was to remove the hard drives from
> > the dead server & swap them for the hard drives of the running server
> > (SCSI RAID enclosures with hot-swapable drives). I didn't hot swap them,
> > but powered everything down, swapped the drives & restarted the good
> > server.
> >
> > All was right with the world until I discovered that I had no network
> > connectivity -- which meant I was back to being screwed, again. After
> > about two hours of fumbling in the dark I finally figured out what was
> > happening. Udev was now assigning my network ports as eth3, eth4 & eth5,
> > instead of 0, 1, & 2. Since this didn't match was was configured in
> > interfaces, the ports were not being initialized. After editing the
> > interfaces file accordingly, I had network access again and this behavior
> > repeated itself through several subsequent reboots.
> >
> > Finally, my question is why was udev reassigning the port names? Here's a
> > snippet of the dmesg file:
> >
> > [   40.526949] ACPI: PCI Interrupt 0000:03:08.0[A] -> GSI 18 (level, low)
> > -> IRQ 18
> > [   40.630945] e100: eth0: e100_probe: addr 0xfeafb000, irq 18, MAC addr
> > 00:e0:81:29:ae:1b
> > [   40.630945] tg3.c:v3.92.1 (June 9, 2008)
> > [   40.630945] ACPI: PCI Interrupt 0000:02:09.0[A] -> GSI 24 (level, low)
> > -> IRQ 24
> > [   40.647089] udev: renamed network interface eth0 to eth3
> > [   40.651233] eth0: Tigon3 [partno(BCM95704A7) rev 2003 PHY(5704)]
> > (PCIX:100MHz:64-bit) 10/100/1000Base-T Ethernet 00:e0:81:29:ae:5e
> > [   40.651410] eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[0]
> > WireSpeed[1] TSOcap[1]
> > [   40.651562] eth0: dma_rwctrl[769f4000] dma_mask[64-bit]
> > [   40.654946] ACPI: PCI Interrupt 0000:02:09.1[B] -> GSI 25 (level, low)
> > -> IRQ 25
> > [   40.671169] usb 1-2: new full speed USB device using ohci_hcd and
> > address 2 [   40.677140] eth1: Tigon3 [partno(BCM95704A7) rev 2003
> > PHY(5704)] (PCIX:100MHz:64-bit) 10/100/1000Base-T Ethernet
> > 00:e0:81:29:ae:5f [   40.677318] eth1: RXcsums[1] LinkChgREG[0] MIirq[0]
> > ASF[0] WireSpeed[1] TSOcap[1]
> > [   40.677470] eth1: dma_rwctrl[769f4000] dma_mask[64-bit]
> > [   40.680862] udev: renamed network interface eth0 to eth4
> > [   40.708863] udev: renamed network interface eth1 to eth5
> >
> > If I'm reading this correctly, each port was initially assigned the usual
> > eth0, 1 or 2, but then almost immediately renamed eth3, 4 or 5.
> >
> > Here is my interfaces file:
> >
> > # This file describes the network interfaces available on your system
> > # and how to activate them. For more information, see interfaces(5).
> >
> > # The loopback network interface
> > auto lo
> > iface lo inet loopback
> >
> > # The first 100/1000 kbps ethernet nic
> > auto eth4
> > iface eth4 inet static
> >        address 192.168.168.11
> >        netmask 255.255.255.0
> >        hwaddress ether 00:E0:81:29:AE:5F
> >        gateway 192.168.168.168
> >
> > # The 10/100 kbps ethernet nic
> > auto eth3
> > iface eth3 inet static
> >        address 192.168.168.10
> >        netmask 255.255.255.0
> >        hwaddress ether 00:E0:81:29:AE:1B
> >        pointopoint 192.168.168.13
> >        up route add -host 192.168.168.13 dev $IFACE
> >        down route del -host 192.168.168.13 dev $IFACE
> >
> > # The second 100/1000 kbps ethernet nic
> > auto eth5
> > iface eth5 inet static
> >        address 192.168.168.12
> >        netmask 255.255.255.0
> >        hwaddress ether 00:E0:81:29:AE:5E
> >        pointopoint 192.168.168.9
> >        up route add -host 192.168.168.9 dev $IFACE
> >        down route del -host 192.168.168.9 dev $IFACE
> >
> > I almost left out, that since the MAC addresses were different I had to
> > edit the interfaces file to correct for that, but that didn't cause or
> > correct the udev renaming.
> >
> > If you've read this far, then very sincerely, thanks for your patience
> > and any insights you may have. I'm up and running, but I really would
> > like to understand what is happening here.



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Debian 'Lenny' - Registered Linux User #241964
--------
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