WiFi Nightmares!

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RAID: What You Should Know, and Probably Don't.

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Should You Turn Your Computer Off Or Leave It On?


This is a basic concern of all computer owners: how to make the computer last longer. Unfortunately, the answer is more complicated than the question. Some say that if you leave the computer running all the time, it will fail sooner. Others say constantly turning it on and off will break it. The problem is they're both right.

There are two measures of reliability: Mean Time Between Failures (MTBF) and Mean Cycles* Between Failures (MCBF). If you turn something on and leave it on, you've only cycled it once, so you will reach the MTBF first; if you keep turning something on and off, you've hardly used it, but you'll reach the MCBF first.

In general, mechanical components will fail sooner the more you turn them on and off (cycle them). As an example, automobiles which have 100,000 miles on them can be in pretty good shape if all the mileage is highway driving, but automobiles with only 50,000 miles can be wrecks if all the mileage is from stop-and-go city driving. Electronic components, however, will generally fail after they have been powered on for a certain (lengthy) amount of time, regardless of how often you turn them on and off. The problem with computers is that they are made up of both electronic (CPU, RAM, etc.) and mechanical components (hard disk drive, fan, power switch). If you leave the computer running all the time, you will reach the MTBF of the electronic components; if you turn the computer on when you need it, and turn it off every time you're done, you could reach the MCBF of the mechanical components.

My suggestion is that you turn the computer on the first time you need it, and turn it off after the last time you use it. Turning it on (or leaving it on) when you don't need it, will shorten its life, but turning it on and off too many times will also shorten its life.

*A cycle is a change in the operating state of a device. The simplest example is turning something from off to on, but also can include a variety of operating states, such as: standby, sleep, etc.

Power Protection

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Connectors


Quite frequently, a computer will fail, and simply disconnecting everything and connecting it all back up will mysteriously solve the problem. Well, it's really not very mysterious. A connection failed!

Years ago, it was common practice for field repair technicians to simply swap boards which were known to be good, with the boards in the computer that wasn't working. After swapping each board, the technician would test the computer to see if the problem was fixed. If it didn't work, the technician would swap the next board; if it did, the last board swapped was presumed to be at fault as was discarded.

IBM wanted to know what, exactly, was failing on these boards, so it asked its technicians to send the failed boards to a single depot, where the individual components would be tested. What they found was that over 90% of the these boards still worked perfectly! If the technician had simply removed and reinstalled that same board, the computer would have worked.

The reason connectors fail is generally environmental. Often, the connector's copper or gold contacts will oxidize, breaking the electrical connection. Sometimes, during a computer's operation, the components in the case will expand with the increased heat, which can then cause a connection to fail. And sometimes, vibrations from the computer fan, or from other equipment nearby, can cause a connection to shake loose.

This is one of the reasons that laptop computers are slightly more reliable than desktops. Laptop computers include a lot more features which are integrated into the computer logic board, so laptop computers have significantly fewer connections than desktop computers.

Backing up is almost always a waste of time.


Why?

  1. The vast majority of backups will never be needed to restore anything.
  2. A significant portion of the ones that are needed to restore something won't be able to.


Now, I hope that the only reason your backups are a waste of time is reason number 1, but I have seen too many people who have experienced reason number 2. If you are going to bother doing backups, make sure you can do a restore.

A company I know had been doing backups religiously for years. They were routinely swapping tapes in their NetWare server, where a consultant had set up SBACKUP.NLM to run automatically. The consultant had stopped supporting them for one reason or another, and when they needed to restore some important files, they asked me to assist them. When I got there, I examined the setup for SBackup and found that their original consultant had configured it to only backup the operating system directories. There were never any backups of their data!

Another company I know had set up their own backup system and had been using it for years, but when they needed to restore some important files, they called me. I found that they had only ever been backing up changed files. They had a drawer full of tapes, and they didn't know when the files they needed were last changed. I spent hours, with half the corporate staff hovering over me, searching every tape in the drawer for the files they needed. Some of the tapes had failed, and I never did find all the lost files.

If you're going to invest your time and effort in performing backups, make sure you can use them to do a restore. It's simple. Before a regularly scheduled backup, make a copy of a small subdirectory. After the backup has been performed, delete the copy and try to restore it from the backup.

© 2013 T C Solutions, Inc.
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