Posted by: Dakusan
« on: September 28, 2009, 05:31:52 am »Originally posted on: 08/29/08
I am still, very unfortunately, looking into the problem I talked about way back here :-( [not a lot, but it still persists]. This time I decided to try and boot the OS into a “Safe Mode” with nothing running that could hinder performance tests (like hundreds of HTTP and MySQL sessions). Fortunately, my friend whom is a Linux server admin for a tech firm was able to point me in the right direction after researching the topic was proving frustratingly fruitless.
Linux has “runlevels” it can run at, which are listed in “/etc/inittab” as follows:
# Default runlevel. The runlevels used by RHS are:
# 0 - halt (Do NOT set initdefault to this)
# 1 - Single user mode
# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)
So I needed to get into “Single user mode” to run the tests, which could be done two ways. Before I tell you how though, it is important to note that if you are trying to do something like this remotely, normal SSH/Telnet will not be accessible, so you will need either physical access to the computer, or something like a serial console connection, which can be routed through networks.
So the two ways are:- Through the “init” command. Running “init #” at the console, where # is the runlevel number, will bring you into that runlevel. However, this might not kill all currently unneeded running processes when going to a lower level, but it should get the majority of them, I believe.
- Append “s” (for single user mode) to the grub configuration file (/boot/grub/grub.conf on my system) at the end of the line starting with “kernel”, then reboot. I am told appending a runlevel number may also work.
