Monday 10 December 2007

SBS - No Graceful Shutdown? Be Prepared ...

If the server does not have a UPS capable of at least shutting the server down gracefully ... what happens?

Well, if one of the hard drives in a RAID 1 array was just a little flaky, then it is very likely that the shock shutdown may kill it.

Or, if there were some sort of OS corruptions hanging in the balance, they may show themselves with a no boot situation.

How do we know that one of the drives is flaky after the power outage?

The OS will take an inordinately long time to boot, and may, or may not, have a service failed error after the outage.

So, in this scenario we can discover very quickly two of our weakest links:
  • UPS is not big enough to gracefully shutdown the server after a predetermined amount of time
  • Our backup restoration method has not been tested yet and it fails.
Or, if the UPS has no A/C power filtration capabilities at all, it may let the subsequent series of spikes through to the server when the power comes back up. This in turn may cause a problem. Keep in mind that the initial spikes may get filtered out by the existing UPS, but the smaller subsequent ones may not.

So, we learn a very valuable lesson:
  1. Have a UPS in place that is big enough to allow for a graceful server shutdown
  2. Have a UPS or UPSs in place that properly filters all A/C power or other power sources heading into the server including:
    • Telephone for fax and/or DSL
    • COAX for cable Internet
    • CAT 5E for all server ports
    • Network switches, DSL/cable modems, etc protected.
  3. Workstations have at least a 3K+ Joule surge arrest in place on their A/C, CAT 5e, and telephone if needed.
  4. Workstations used for database work have at least a 1000VA UPS with filtration in place for graceful shutdown of the database.
After installing a new UPS, one of the first things to do beyond the UPS' own self-test routine is to test it. We need to know how that UPS is going to behave in the environment it will be protecting. Unplug it after at least 24 hours after delivery and setup to give it enough time to go through a charge cycle.

Sometimes a factory defect may not show itself until the UPS flips over to battery mode for an extended duration. So, it is better to know that the unit is going to fail before an actual power event brings a defect out and causes even more grief.

Philip Elder
Microsoft Small Business Specialists

*All Mac on SBS posts are posted on our in-house iMac via the Safari Web browser.

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