Troubleshooting is a form of problem solving, often applied to repair failed products or processes.

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19
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9answers
6k views

Your troubleshooting rules, approach to troubleshooting? [closed]

Do you have any general rules that you fall back on when you troubleshoot a difficult network/hardware/software problem? Eg: "I isolate the source of the problem by testing a peripheral with a second ...
62
votes
8answers
32k views

Environment variables of a running process on Unix?

This is to troubleshoot some problems related to environment variables .. On Windows, I could do this by using tool such as ProcessExplorer to select particular process and view values of each ...
11
votes
7answers
11k views

Troubleshooting a “slow” network

We've all had a complaint that the "network" is "slow" at some point: might be localized to one room (switch) or one computer, might just be Internet (DNS? Browser issue?), might be just one ...
14
votes
2answers
22k views

page allocation failure - am I running out of memory?

Lately I've noticing entries like this one in the kern.log of one of my servers: Feb 16 00:24:05 aramis kernel: swapper: page allocation failure. order:0, mode:0x20 This is what I'd like to know: ...
16
votes
10answers
2k views

Etiquette of Troubleshooting Problems In The Workspaces Of Others

A visibly upset colleague approached our technical support team this morning. She noted a member of our team had changed her workspace: Her monitor was turned off (she expected standby mode). Her ...
2
votes
4answers
243 views

Diagnose Network Faults

Disclaimer: I am a developer, not a system admin, please be gentle. Where I work we are having a lot of intermittent network problems. Sometimes the DNS will fail, but access to servers can be done ...
11
votes
1answer
477 views

Harddisks falling offline for unknown reason

I have 7 systems running the setup below. Now and then a different disk falls offline, but on closer inspection the disk is good and not faulty and works flawlessly for at least another year. Since ...
10
votes
6answers
18k views

Why was my ping answered by a different IP address than the one pinged?

While trying to setup a MSSQL clustering solution, I am running into a problem that is outside of my expertise that is related to networking. I was trying to find a free IP to used for my node. I ...
4
votes
2answers
435 views

Troubleshooting apache redirects in production

How do you troubleshoot Apache redirects in production? I know there's a logging feature somewhere that lets you log all the redirects that happen...
10
votes
12answers
563 views

What's the first thing you check when an untouched unix server starts going berserk?

So you have this neatly setup unix server and it's super fast and works swell and everything is great for months, and suddenly all kinds of weird errors start showing up for a variety of different ...
8
votes
3answers
1k views

Performing root-cause analysis

I want to learn more about how to perform root-cause analysis. More times than not, our department tells the user to try rebooting (thier Windows XP system), which actually "fixes" a good number of ...
8
votes
4answers
6k views

Slow network speeds - what should I check?

Users are reporting that it's taking a long time to access files on the network, browse intranet sites, etc. What should I check?
2
votes
3answers
14k views

Best way to troubleshoot apache not starting?

We have recently gotten a backup server to mirror all our data onto in case the primary server goes down. I've gotten all the sites data updated through rsync, and all the apache config and databases ...
3
votes
5answers
2k views

How can I troubleshoot a broken on/off switch?

I have a file server that was recently relocated in a transoceanic move. It isn't under warranty, as it was a custom-built in-house tower. When I hooked everything up and tried to boot it, the system ...
2
votes
2answers
3k views

How to change SMP affinity of an IRQ on Ubuntu PV domU inside Xen XCP?

I'd like to change IRQ SMP affinity for reasons, outlined in this question: CPU0 is swamped with eth1 interrupts But I can't — I see Input/output error when I try to write to ...
2
votes
8answers
9k views

How can I install Windows 7 without burning a DVD or using a USB Drive?

I downloaded the .iso of Windows 7 and would now like to install it as my main OS. However I can't because I don't have a DVD Burner, a 2+ GB USB Drive, or a external HDD (or extra HDD). So how can I ...
2
votes
5answers
1k views

How to troubleshoot hanging linux server

I have several Ubuntu Server 8.04 machines at a remote location. Every couple of months or so, one of them would stop responding and need to be power cycled. From looking at my log files it seems that ...
1
vote
2answers
3k views

How can I capture traffic with tcpdump and a sliding window or sort of “logrotate”?

I want to capture some traffic with tcpdump for troubleshooting. The problem is, the error is not reproducible. To not fill up the hole disks with captures, I would like to capture the traffic with ...
5
votes
3answers
4k views

Troubleshooting linux server reboots?

I have a Linux server I've just set up, debian squeeze, 2.6.32-5-amd64, and over the past week it's rebooted three times, twice in one day. There was no power outage that I am aware of (and it's ...
4
votes
2answers
2k views

Cannot mount /dev/sdc1 on Debian 5.0, special device /dev/sdc1 doesn't exist

I'm trying to fix an odd problem I'm having that I've never seen or heard of before. I have a disk, /dev/sdc and I'm trying to mount it, but cannot. sudo mount /dev/sdc1 /mnt mount: you must ...
3
votes
1answer
1k views

Troubleshooting Windows Server 2012 storage spaces

I'm trying the new "Storage Pools" feature on Windows Server 2012, and I've created several disks on the pool. When I restart the server, some of the disks (two, out of four) do not attach ...
2
votes
2answers
1k views

Diagnosing Hardware Problem in Linux Server that's Kernel Panicking

We have a server that has been occasionally kernel panicking for a while now that we believe has a hardware problem. How would you go about troubleshooting hardware that you don't have physical access ...
2
votes
4answers
486 views

Tracking down load average

The "load average" on a *nix machine is the "average length of the run queue", or in other words, the average number of processes that are doing something (or waiting to do something). While the ...
2
votes
2answers
7k views

Can someone see why my DNS won't work? I followed everything in the tutorial, but won't work

If anyone can help me troubleshoot this, I would very much appreciate it!! The tests work. It's just that when I do the manual ping/nslookup test, nothing is working. By the way, I followed ...
1
vote
2answers
1k views

Why does samba server fail to start with PANIC error?

I'm seeing an error when trying to start smbd: # smbd -i smbd version 3.2.5 started. Copyright Andrew Tridgell and the Samba Team 1992-2008 ...
1
vote
5answers
1k views

What is the root cause of a Hard Drive “ticking” sound after 15 min of being on?

In my office there is a laptop dell inspiron 1420 with HD of 100GB of space. The computer is about a year old, and the hard drive has a weird and annoying ticking sound. The ticking sound starts ...
0
votes
1answer
327 views

Why my 2nd ip from traceroute is not answering the ping anymore? [closed]

My Internet is really laggy today, I did a tracerout and I realize that I'm having no answer from an ip at the beginning of the traceroute. see: Tracing route to 12.129.202.154 over a maximum of 30 ...
0
votes
2answers
2k views

How can I diagnose an Ubuntu system freeze after reboot

One of our servers froze yesterday, apparently refusing to serve any HTTP requests. The tech guy on site could not connect remotely to the machine, so he rebooted the (virtual) machine from the VMware ...
0
votes
7answers
727 views

Good tools and approaches for diagnosing poor performance

My company is developing a web-based data viewer application which requires a fairly decent amount of bandwidth to function well. However recently we have been changing a lot of things. For example, ...
0
votes
6answers
741 views

Debugging Cisco 2621 Routers

I've recently noticed problems with my 2621 router - it becomes unresponsive for about 10 minutes at a time, about 10 times a month. The router sits inbetween the outside world and servers which I ...