BAUMLER'S LAW OF SYSTEM ADMINISTRATION

It never hurts to reboot during scheduled downtime

High availablility and high uptimes are all very well, but what really matters is that the system is available when needed. For several years, I ran a system where a key application had a memory leak but only had to run from approximately 6:45 am to 11:15pm; we rebooted daily at about 11:15 pm and that application was stable. My uptime averaged 23:45, but we beat our application availability requirements.

I'm not impressed with 5-9's of uptime, if you get it by going to single user mode, doing maintainence and then booting back to run level 2 or 3. I'm not impressed with 5-9's of uptime, if you never patch, `cause you'd lose your uptime. I'm impressed with 5-9's of application availability, measured by your customer's business need for the application. Reboot all you want, just meet the business needs.

Corollary

Sometimes the fastest way to get a system back into service is to reboot

In the last year, I've seen several situations where a system has been having a problem and there is a known, elegant solution that will take approximately 20 minutes to implement and test before users can access the system again; or a reboot (15 minutes max) will fix the problem. Similarly, sometimes there is a 10 minute solution that might work, but if it doesn't you'll have to reboot - why not reboot right now, you know you'll be up in 15 minutes max.

jlb August 15, 2002