Avoiding File Corruption

No matter how well you maintain your system, there comes the time when it freezes up.  When that happens, you really have no choice other than to do a hard reset, by turning the power off, and back on.  Since there is an inherent risk that this will result in some file corruption, it should be avoided if at all possible.  Still, sometimes it is necessary.

There are many times, however, when your system is not truly frozen, but is overloaded instead.  This is more common in a network environment, when users are running software that is server based.  In this case, it may appear to be frozen, as users get no response at their workstations.  However, what may really be happening, is that the server has become so busy, that it does not have time to respond to the requests from the workstation.  The appearance to the users is the same, but true cause is different.

The difference is important, because if it is a matter of server overload, many times the process causing the overload can found and killed.  If this can be done, the risk of corrupting your data files is much less than if the system is simply powered down.  The reason for this is that when a process is killed, in most cases, it closes the files that it has open as it goes down.  If the power is simply shut off, this does not occur.

Check your system for any indications of activity, to determine if it is overloaded as opposed to being frozen.  In most cases, an overloaded system will have high disk usage.  You may be able to hear the disk drive working, or the disk activity light on the computer may be blinking very fast, or even on solid.  If that is the case, then you have a good chance of being able to get on and kill the process.

When a server is overloaded as opposed to being frozen, most times it is possible to get log in, and run utilities to identify the runaway process.  It may be very slow responding, but if all possible give it enough time and you will eventually get logged in.  Running the utilities to identify the runaway process varies, depending on whether you are on a Windows based machine, or UNIX/Linux.  I will go into the utilities used for this in a future blog. For now, just be aware that the utilities will probably also be slow to respond.  However, if you can get logged in, and the utilities do respond, you can probably kill the offending process, and free the system back up.

There may be times that the server is so overloaded, that you will not be able to log in and kill processes.  In that case, you will have to resort to turning the power off, and risk corrupting files, but you really have no choice at that point.  This should be a last resort, and only done if you are not able to get into your system at all.