[CentOS] RAID level and killing a job

nate centos at linuxpowered.net
Tue Jan 13 18:04:18 UTC 2009

Scott R. Ehrlich wrote:
> First question - under CentOS 5, if I created non LVM partitions on a server
> with 6 disks - 2 disks are RAID 1 (OS), how do I remind myself or inquire
> the
> type of RAID of the remaining 4 disks (RAID 1 or RAID 5), without having to
> reboot?

If they are 4 independent disks then you should just see them as
standalone disks, if they were in RAID 1 or RAID 5 there would not
be 4 disks, there might be 2 for 2xRAID 1s, or 1 with RAID 5. Assuming
your using hardware raid of course. If you are using hardware raid depending
on the controller/driver you can query it for it's configuration. If
your using software raid it should be pretty easy to determine it's
configuration as well(last I ran software raid I would just cat /proc/mdstat)

> Second question - A newly installed server consisting of CentOS 5.2,
> straight
> off the DVD, I invoke a command by hand, realize I want to kill it soon
> after
> (logged in as root).  I issue ps auwx|grep name_of_command, get the PID, and
> issue kill -9 PID.  ps auwx|grep name_of_command is still running.
> The command is NOT part of any scheduled job.    Why won't the process die?

Is the process state "D" or "Z" ? Frequently either of these states
can trigger an unkillable process. Sometimes "Z" (zombies) can be
killed but often times they can't be directly killed. And if the
process is in "D" then it is stuck waiting for I/O(most often) and
you have to wait for it to complete, or reboot, sometimes going to
single user mode and back again works as well, and sometimes killing
other processes that the stuck one depends on can sometimes free it
up so it can die.

If the process is zombied you can try to find the parent process (if
there is one) with ps -efx, and kill that sometimes that can cause
the child to die as well, doesn't always work though.


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