How full is too full?

We have had several calls in the past week in which the client cannot boot their computer after a crash. When they use their System CD to restart their computer and run Disk Utility, they are met with the message that their disk catalog is corrupted and it cannot be repaired. So what is going on? How can a drive that was working suddenly just stop working?

When they call and we begin unraveling their problem, some will tell us that they were downloading a huge file from the Internet. Others will recount that they had been seeing a message that indicated that their startup drive was almost full, but they did not know what to do, so they ignored it or they were waiting to call us in the morning. What should they have done? When is a hard drive too full?

The old rule of thumb said to keep 10 to 15% of your hard drive empty. That rule worked pretty well on my old iMac with its 80 BG hard drive, but on my new Mac, that would mean I should keep a whopping 32 to 48 GB empty!

So how much empty space do you really need? First of all let's examine why your computer needs empty space.

My every day working computer is my MacBook Pro. Apple sold it to me with a 160 GB hard drive, but when I use the Get Info command I see that its true capacity is 148.73 GB. So what happened to the missing 11 GB?

There are two ways to express hard drive storage capacity. The easy way is to say that 1 GB = 1000 MB. However, ask any geek, and they will inform you that 1 GB really equals 1024 MB. Many years ago, hard drive manufacturers began rounding hard drive capacity numbers and "forgetting" that extra 24. Part of my "missing" space is lost in that calculation. Still more space is occupied by the directory files that the drive creates to keep track of the files that are store on the drive. So, by the time we account for the fuzzy math and the required files, my 160 GB drive has a capacity of 148 GB.

So let's apply this information to the minimum amount of hard drive space you need to have empty on your computer. First, from experience, I know that my computer begins to slow down when it has less that 15 GB of empty hard drive space. When I have 10 GB of space left, I find that I get many spinning colored balls and programs quit unexpectedly. If I get down to 5 GB left, my computer becomes very unstable and freezes frequently.

If you have less than 5 GB of hard drive space left, there is a great chance that your hard drive will crash.

So how can you check to see how much room is left on your hard drive? At the bottom of every finder window there is an indicator of how much space there is on your hard drive:

As you can see, my hard drive has less that 20 GB available. It is once again time for me to do a little hard drive cleaning!

In a future post I will show you ways to make room on your hard drive. If you can't wait, we can give you a hand at Bob LeVitus Consulting. Check out our site and give us a call!