Re: [CentOS] Centos machine sometimes unreachable
On Wednesday, August 22, 2012 09:20:20 AM m.r...@5-cent.us wrote: Good thought! Could someone have moved non-computer hardware, like, say, a desk or chair, or there's been some utility work, and the cable run's impacted occasionally... or stepped on? Or even vibrated loose. As a lesson in 'vibrational torque' aka the 'whimmy diddle effect' (see https://en.wikipedia.org/wiki/Gee-haw_whammy_diddle ), I'll relate what happened to a machine in our newly rennovated Research Building Data Center. The machine in question is an EMC Clariion CX3-80 with three 40U racks. Each rack needs two 30A 208V single-phase circuits. Due to the way the electrical was run for this machine, one UPS is powering one side of the three cabinets, and a second, smaller UPS is powering the other side. The secondary feed's L6-30R's are mounted to the pedestals of the raised floor; the primary feed's L6-30R's are in cast aluminum pendants lying on the subfloor, with the receptacles pointing up. An electrician was drilling two 1/4 inch holes for concrete anchors for a conduit run sixteen feet away from the CX3-80 a couple of days ago, and I started getting a bunch of alerts from the CX3-80. I looked at the array, and yellow lights were lit on all three cabinets. Hmm, what's up with that; power loss to the whole side of the array? I lifted the panel over the L6-30R's in the pendant on the subfloor, and all of the twist-lock plugs were unplugged from their pendant receptacles! No one was in the data center but the electrician, and the power was fine right before he started drilling the two small holes. I personally had plugged in the plugs that morning, and had set the cords to apply the correct torque to maintain the twistlock, and had fully seated and locked the plugs in the receptacles. The vibration of the hammer drill sixteen feet away hit the right resonance, and 'whimmy diddled' the plugs out of their receptacles. Thermal cycling can also exert torques, and one of my preventive maintenance steps in all of our data center spaces with twist lock plugs is to reseat the twistlock once per quarter. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
2012/8/22 Les Mikesell lesmikes...@gmail.com On Wed, Aug 22, 2012 at 8:01 AM, Richard Reina gatorre...@gmail.com wrote: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? What does ethtool say about your duplex setting Here is the output from ethtool Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 1 Transceiver: internal Auto-negotiation: on Supports Wake-on: g Wake-on: g Current message level: 0x0007 (7) Link detected: yes THe switch is a linksys etherfast 3124 that has worked perfectly for 10 years. I don't know anything about it's settings. This is a LAN with about a dozen machines. Thanks ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[CentOS] Centos machine sometimes unreachable
I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? Thanks, Richard ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
Am 22.08.12 15:01, schrieb Richard Reina: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? Recently I was faced with a similar problem (cant ping a device from time to time which was not touched for about two years...). My solution: check the lan cabel. The system I had problems with had been standing in the sun behind a window and the lan cabel was 'melting' and did not fit properly into the adapter. my2cents. -- Götz Reinicke . Filmakademie Baden-Württemberg GmbH ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
Richard Reina wrote: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? Have you done an ifconfig on 5, and seen if there's any collisions, etc? Another possibility is that *you* haven't changed, but someone else has put a piece of hardware on the LAN that's trying to get that IP, or has it configured for that IP. mark, who *really* wishes that the network folks would give their hardware IPs by MAC, not broadcast ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
Götz Reinicke wrote: Am 22.08.12 15:01, schrieb Richard Reina: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping snip Recently I was faced with a similar problem (cant ping a device from time to time which was not touched for about two years...). My solution: check the lan cabel. The system I had problems with had been standing in the sun behind a window and the lan cabel was 'melting' and did not fit properly into the adapter. Good thought! Could someone have moved non-computer hardware, like, say, a desk or chair, or there's been some utility work, and the cable run's impacted occasionally... or stepped on? mark ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
On 22/08/2012 14:01, Richard Reina wrote: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? I had this problem in the past and found that it seemed to be due to iCMP rate limiting. We were pinging a lot of hosts from the monitoring system, however... But you might want to investigate here: http://www.kernel.org/doc/man-pages/online/pages/man7/icmp.7.html -- Regards, Giles Coochey, CCNA, CCNAS NetSecSpec Ltd +44 (0) 7983 877438 http://www.coochey.net http://www.netsecspec.co.uk gi...@coochey.net ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
Look like there are some errors although I am not sure what the mean. eth0 Link encap:Ethernet HWaddr 00:D0:B7:5A:C6:FE inet addr:192.168.0.5 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::2d0:b7ff:fe5a:c6fe/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2316067887 errors:0 dropped:0 overruns:1 frame:1 TX packets:2451037674 errors:3 dropped:0 overruns:0 carrier:3 collisions:0 txqueuelen:1000 RX bytes:221599111550 (206.3 GiB) TX bytes:575914174697 (536.3 GiB) loLink encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:1197938537 errors:0 dropped:0 overruns:0 frame:0 TX packets:1197938537 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:109601534433 (102.0 GiB) TX bytes:109601534433 (102.0 GiB) Cable seems fine and machine is in a dark room (no sunlight) although it does run through the ceiling. 2012/8/22 m.r...@5-cent.us Richard Reina wrote: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? Have you done an ifconfig on 5, and seen if there's any collisions, etc? Another possibility is that *you* haven't changed, but someone else has put a piece of hardware on the LAN that's trying to get that IP, or has it configured for that IP. mark, who *really* wishes that the network folks would give their hardware IPs by MAC, not broadcast ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
Richard Reina wrote: Look like there are some errors although I am not sure what the mean. eth0 Link encap:Ethernet HWaddr 00:D0:B7:5A:C6:FE inet addr:192.168.0.5 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::2d0:b7ff:fe5a:c6fe/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2316067887 errors:0 dropped:0 overruns:1 frame:1 TX packets:2451037674 errors:3 dropped:0 overruns:0 carrier:3 collisions:0 txqueuelen:1000 RX bytes:221599111550 (206.3 GiB) TX bytes:575914174697 (536.3 GiB) Cable seems fine and machine is in a dark room (no sunlight) although it does run through the ceiling. Please stop top posting. I'm not sure, but overrun? Frame? Not sure. Cabling goes into the ceiling... was there any wiring or HVAC work done lately, where the cables might run? mark 2012/8/22 m.r...@5-cent.us Richard Reina wrote: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? Have you done an ifconfig on 5, and seen if there's any collisions, etc? Another possibility is that *you* haven't changed, but someone else has put a piece of hardware on the LAN that's trying to get that IP, or has it configured for that IP. mark, who *really* wishes that the network folks would give their hardware IPs by MAC, not broadcast ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos machine sometimes unreachable
On Wed, Aug 22, 2012 at 8:01 AM, Richard Reina gatorre...@gmail.com wrote: I have a simple perl script that every few hours pings the handful of machines on my LAN. Lately I've sometimes been getting ping of 192.168.0.1 succeeded ping of 192.168.0.7 succeeded ping of 192.168.0.5 FAILED ping of 192.168.0.6 succeeded ping of 192.168.0.9 succeeded This machine in question has been running Centos faithfully for about six years and no recent changes to it have been made. When I try and ping the machine manually it works. /var/og/messages does not seem irregular. Does anyone know know what might be the problem or what else I might check? What does ethtool say about your duplex setting, and is the connected switch set one way or the other? In the long distant past, cisco switches weren't very good about negotiating and they recommended configuring full duplex at both ends of the connections. Now the hardware and standards are better and everyone uses auto, but you might have an old switch or an old configuration somewhere in the path. The problem is that if one end of the connection is set to not negotiate, the other end will pick half duplex and the mismatch will cause trouble at random. -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
