How many of you out there know the time settings on your Cisco network and SAN switches? Are they keeping the correct time? Is NTP setup properly? Is your timezone settings proper? You might ask why one should care. Proper timestamps can help you correlate events as they happen. Having to play around with offsets because time isn’t proper can be a pain. “That switch is 3 hours behind so when it said it lost as power supply at 2am, it was really 11pm….yesterday.”
Figure out whether you want your date/timestamps to be synced to a single timezone (say, UTC) or your local time. Local time can get interesting if you have devices spread out in multiple timezones. Then setup NTP to sync time. The last bit is to make sure you are using the proper time. This goes for SAN switches as well as network switches (both running NX-OS):
clock timezone EST -5 0
clock summer-time EDT 2 Sunday March 02:00 1 Sunday November 02:00 60
The first line sets your timezone it EST which is 5 hours and 0 minutes behind UTC. Set your timezone to Standard Time and modify it for Daylight Savings with the second line. If your clock timezone line is using Daylight Savings Time, it won’t change back to Standard Time once Daylight Savings Time is over.
The second line is the line that actually sets up Daylight Savings Time. Thanks to the US government fooling around with the timing of Daylight Savings Time, we need to change it from what used to be default accepted norms. Most vendors decided to come up with a method of customizing it instead of hard coding it once again should the government decide to change it again. The second line basically says “Change to Daylight Savings Time on the second Sunday of March at 2am and change back on the first Sunday of November at 2am. Change it by an hour.”
By making time consistent across your switches, you will be able to rely on the actual timestamps when you need them. That is one less headache when trying to troubleshoot things.
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