The real merit of the vmcore is that you can trace the code with the current value each variable holds. Here you can find one example that traces the filesystem which ended up with the corrupted data entry somehow. http://pagead2.googlesyndication.com/pagead/show_ads.js crash> bt PID: 6326 TASK: ffff810402165820 CPU: 1 COMMAND: "fuser" #0 [ffff8103b54efa80] crash_kexec at ffffffff800b099c… Continue reading Jump into vmcore analysis – Step 6
Jump into vmcore analysis – Step 5
With 'bt' command you can check the processes that occupied the CPU at the time of crash. But, there is the time you want to check other processes's backtrace to see what interaction had been established between processes. You can check it by using one of below two methods. crash> set 24960 PID: 24960 COMMAND:… Continue reading Jump into vmcore analysis – Step 5
Jump into vmcore analysis – Step 4
There are times the crash had happened because of the lack of memory. Or times that system had hard time because of the memory issue. To check those, you can use below command. crash> kmem -i PAGES TOTAL PERCENTAGE TOTAL MEM 16464824 62.8 GB ---- FREE 3807386 14.5 GB 23% of TOTAL MEM USED 12657438… Continue reading Jump into vmcore analysis – Step 4
Jump into vmcore analysis – Step 3
Now we are ready to deep dive into vmcore analysis to confirm what went wrong in the system. In general, first thing I'm checking is the system's log. crash> log .... .... end_request: I/O error, dev sdajm, sector 0 end_request: I/O error, dev sdajm, sector 8 end_request: I/O error, dev sdajm, sector 0 NMI Watchdog… Continue reading Jump into vmcore analysis – Step 3
Jump into a vmcore analysis – Step 2
As I had mentioned in the previous article, you can launch crash analysis by running the below command $ crash vmcore vmlinux The order of the file doesn't matter as far as the file exist there. But, there's a time that crash command fails as a vmcore is highly incomplete. In that case, you can… Continue reading Jump into a vmcore analysis – Step 2
Jump into a vmcore analysis – Step 1
If you have a vmcore needs to be analysed, you should have to download related kernel-debuginfo package unless your kernel does have all the debug information in the live kernel. You might easily check the kernel version of the vmcore by run 'uname -r', but safest way would be checking vmcore itself. You can use… Continue reading Jump into a vmcore analysis – Step 1
Life is all about presentation yourself
When I had an interview first time, I passed the paper exam with quite good score. The problem was with the interview. One of my weakness I guess is presenting myself to others. When interviewers asked me what is my selling point, I said 'debugging'!!! I said 'debugging' is the best thing I do well… Continue reading Life is all about presentation yourself
Check IP address of a virtual guest
There's a time you want to check virtual guest's IP, but no way to access the machine as you only have text terminal. You can retrieve IP address by using the following script. #!/bin/bash macaddress=`virsh dumpxml $1 | grep "mac address" | awk 'BEGIN { FS = "=" }; {print $2}' | sed 's//>/ /'`… Continue reading Check IP address of a virtual guest
Build a OpenStack on VMware Fusion 5
Cloud is a big trend in recent years and it will be bigger and bigger. Even though you want to join in this trend, it's hard as it requires lots of machines to build and test it. Fortunately, these days virtualisation technique allows us to install virtual guest on top of another virtual quest. So,… Continue reading Build a OpenStack on VMware Fusion 5
How to use fixed DHCP address on VMware Fusion 4/5
There's a time you want to use fixed address even for your NATed VM guest. In the case of VMware, you can achieve this by modifying configuration file in '/Library/Preferences/VMware Fusion/vmnet8'. vmnet8 is the virtual interface for NATed guests. You can find what ranges are currently applied for this virtual guests by checking dhcpd.conf. $… Continue reading How to use fixed DHCP address on VMware Fusion 4/5
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How to keep record the commands executed by root
If you want to keep record of the commands executed by root account, you can achieve that by using audit rules. First, add the below line in /etc/audit/audit.rules -a entry,always -S execve -F uid=0 http://pagead2.googlesyndication.com/pagead/show_ads.js And restart auditd to apply the changes $ chkconfig auditd on $ service auditd restart
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