Archive for March, 2010

Problems growing RAID6 MD devices on RHEL5 systems

I attempted to grow an existing RAID6 MD device this week, and ran into the following error when I performed the grow operation: $ mdadm –grow –raid-devices=5 –backup-file=/tmp/mdadmgrow.tmp /dev/md0 mdadm: Need to backup 384K of critical section.. mdadm: Cannot set device size/shape for /dev/md0: Invalid argument It appears the ability to grow a RAID6 device […]

Debugging syslog-ng problems

While debugging the syslog-ng issue I mentioned previously, I needed to be able to observe the syslog-ng pattern matches as they occurred. The syslog-ng daemon has a couple of useful options to assist with this. The first is the “-e” option, which causes the daemon to log to stdout. The second is the “-F” option, […]

Breaking down system time usage in the Solaris kernel

I am frequently asked (or paged) to review system performance issues on our Solaris 10 hosts. I use the typical set of Solaris performance tools to observe what my systems are doing, and start drilling down once I know if the problem is with userland applications or in the kernel itself. When I observe issues […]

Great write-up on AMD’s RVI (Rapid Virtualization Indexing) hardware assisted virtualization feature

I came across an awesome Q&Q where Tim Mueting from AMD described the hardware virtualization features in AMD Opteron CPUs. The following excerpt from the interview was especially interesting: “Prior to the introduction of RVI, software solutions used something called shadow paging to translate a virtual machine “guest” physical address to the system’s physical address. […]

Viewing the scripts that run when you install a Linux RPM

RPM packages contain the ability to run scripts after a package is added or removed. These scripts can perform actions like adding or removing users, cleaning up temporary files, or checking to make sure a software component that is contained within a package isn’t running. To view the contents of the scripts that will be […]

Creating a bootable OpenSolaris USB thumb drive

This past week, I had the need to install opensolaris on a host using a USB thumb drive. To create a bootable USB drive, I first needed to snag the distribution constructor tools via mercurial (I ran these commands from an OpenSolaris host): $ pkg install SUNWmercurial $ hg clone ssh:// The caiman slim source […]

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