Understanding mpstat and vmstat output with DTrace

I have been playing with DTrace now for 4 – 5 months, and have created numerous notes to help me remember the probes that can be used to understand vmstat and mpstat output. To ease life in the future (finding this stuff at 3am when a “situation” arises is a pain), I wrote a DTrace mpstat and vmstat cookbook titled Understanding mpstat and vmstat with DTrace. Hope folks find this useful.

Apache logging options

If you use Apache version 2.X, I would recon you are using mod_log_config to log request information to the access_log (if you are not using mod_log_config, I assume you are a busy site that has disable logging to boost performance). This is a nifty module, and after reading the source (the source for mod_log_config is located in $SRCROOT/modules/loggers/mod_log_config.c) I learned that this module has TONS of nifty options to control what gets logged. In addition to logging request data and browser information, you can also log cookie data, request processing time (this requires mod_status and ExtendedStatus), HTTP headers, notes, IP addresses, ports, and numerous other options. If you are using logfile analysis utilities that require Custom/Combined formatted access_logs, you need to be careful where you add these options to avoid breaking your reporting tools. Apache is swell!

Can a SysAdmin use one OS?

I j ust finished upgrading my personal x86 laptop to FreeBSD 6.0, and got to thinking about how many Operating Systems the average system administrator uses. I use OS X on my home desktop, Fedora Core on my work desktop, FreeBSD on my x86 laptop, OpenBSD on my Firewall, and Solaris 10 on everything that needs killer debugging tools and high levels of reliability. I guess this is why I find lots of fun problems to debug. ;)

Fixing FreeBSD /etc/rc.conf typos

I just finished installing gnome 2.12 this afternoon on my FreeBSD 6.0 desktop, and wanted to reboot the system to test out the gdm_enable line I added to /etc/rc.conf. When I rebooted the box, I was greeted with the following error:

Loading configuration files.
/etc/rc.conf: 20: Syntax error: Unterminated quoted string

Ack — it looks like I forgot to properly quote the “YES” value of the name=value pair in /etc/rec.conf. I thought to myself, no problem, I will just fire up vi and fix this anomaly:

$ vi /etc/rc.conf
ex/vi: Error: /var/tmp/vi.recover: Read-only file system

Ack — now the file system is mounted Read-only and I need to write to it! Not to fear, mount’s “-w” option is here:

$ mount -w /

$ vi /tmp/rc.conf
[ edit here ]
:wq!

I have done this numerous times with Solaris using “mount -o remount,” but this was the first time I needed to do this with FreeBSD. Nice!

Concert review: Bon Jovi

I started to get into music in the mid eighties with the big hair band craze, and like everyone used to listen to Bon Jovi. Since I wasn’t able to see them back in their prime, I decided to attend their show last night. The show was awesome, and it was cool hearing classic such as “Livin’ on a prayer,” “Wanted dead or alive,” “Blaze of glory,” “Beds of roses,” “Bad medicine,” “Lay your hands on me,” You give love a bad name,” and my personal favorite “Runaway.” I was amazed at how agile Jon Bon Jovi and Richie were. They were zipping around the stage like bats in the light, and periodically popped up in mysterious locations (e.g., in the middle of the floor) to play songs. Twas a good night, and the concert definitely sent me back to the eighties!

Concert review: Lenny Kravitz / Aerosmith

I attended the Lenny Kravitz / Aerosmith concert last night, and had a fun-filled evening. The show started with Lenny Kravitz taking the stage and cranking out an electrified version of “Where we are runnin”. Lenny continued jamming away in Lenny style, and played numerous hits such as “American Women,” “Can’t get you off my mind,” “Believe,” “Lady” and “Fly away.” When Lenny played “Let Love Rule,” he came out into the crowd to stir people up, and headed back to center stage to end his set with “Are You Gonna Go My Way.” His set list was awesome, and Lenny was definitely having fun jamming!

Once Lenny finished his set and walked off stage, the stage crew prepped the stage for Aerosmith. When Aeromsith eventually came out to start their set, the crowd cheered, and they opened up with the classic hit “Helter Skelter.” Aerosmith was full of energy, and wandered around the stage playing classic hits such as “Dream on,” “Cryin,” “Living on the edge,” “Sweet Emotion,” “Same old song and dance,” “Toys in the attic” and “Walk this way.” It looked like Steven Tyler and Joe Perry were hving fun, and Joe definitely showed that he is a great guitar player. I was somewhat dissappointed that Aerosmith didn’t play “Back in the sadle” and “Janie’s got a gun,” but luckily I got to hear those tunes the last time they came to town.

Aerosmith is always fun to see live, and seeing Lenny Kravits open was awesome!