How would a bad UPS affect only the network port

[Sam Varshavchik <mrsam@xxxxxxxxxxxxxxx>]

I had a curious episode unfold over a course of a week involving a server  
running F18. I'm just trying to solve a little puzzle in the aftermath, as a  
mental excersize.

I went through three bad UPSes. The manufacturer had a bad batch of UPSes.  
> From all appearances they worked when plugged into mains power. The server  
was up and running normally plugged into the UPS, which had mains power, but  
the bad UPSes wre draining their internal battery, even though they had main  
power. Each UPS lasted about a day before its battery went completely dead,  
it started beeping at me, with the server continuing to run on mains power.

Here's the mystery. While I was dealing with that headache, the server  
started to drop off the network, maybe about every 5-6 hours, and stop  
responding to pings. The server itself, from all appearances, was running  
fine. I could log in on the console, everything seems to be working, except  
that it wasn't on the network. ifdown/ifup didn't help, ifup was getting  
stuck getting its IP address from DHCP. The switch had the server port lit,  
and blinking, as it was trying to contact the DHCP server, but the server  
wasn't getting its IP address.

About 20% of the time, unplugging the cable and plugging it back in worked.  
A reboot always worked. The server would reboot, come up on the network,  
have no problem talking to the DHCP server, and run fine for a few hours  
before it stops responding to pings again.

Anyway, while I was dealing with the UPSes, I also thought that I had this  
server's onboard NIC was going bad, and started getting quotes for a  
replacement server. But, after finally putting the server on a good, working  
UPS, it stopped having any kind of problems whatsoever with the network.  
It's perfectly fine.

So, that leaves me wondering how a bad UPS would affect a server's network  
port, and only its network port. As I understand it, with main power, the  
UPS is pretty much out of the loop, and it kicks in only if mains power is  
lost.

Attachment: pgppXNnlwqWkm.pgp
Description: PGP signature

-- 
users mailing list
users@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe or change subscription options:
https://admin.fedoraproject.org/mailman/listinfo/users
Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Have a question? Ask away: http://ask.fedoraproject.org