Whether you use Time Machine or not, you will probably have been irritated by the constant questioning of whether you wish to use an external drive to backup with Time Machine to it.
If this is the case then there is a simple way of disabling this via the command line
Open Terminal & type
sudo defaults write /Library/Preferences/com.apple.TimeMachine DoNotOfferNewDisksForBackup -bool YES
And hit Enter, you will no longer be prompted by Time Machine, if for some reason you miss the prompts then just swap the YES for a NO and you will be presented with them again
Once disabled, you can still choose which disk to use for Time Machine by using the options in System Preferences.
Open System Preferences
click on Time Machine
Click on Select Disk and then choose the disk you wish to use
Now occasionally Mac users are forced to share files with Windows users, and if using an external hard drive you will need to make sure it is readable/writable in both OS’s
So, I was asked this the other day, and it can be quite tricky, basically, you need to boot from an installation disk and run Disk Utility to erase the disk.
Now as the MacBook Air doesn’t have FireWire then Target Disk Mode is pretty much out of the question (although this is now an option on Thunderbolt equipped MacBook Airs), so we will have to either try a remote disk option, or boot from USB.
In this guide I will run through the steps required to complete this task using a bootable USB key, but if you wish to go the Remote Disk option then more info can be found on Apples Support Site at http://support.apple.com/kb/HT2129
For this you will need
Ok, so first of all if you have any data on the USB key, make a backup of any data you have on your USB key
On your Superdrive equipped Mac, insert your Operating System Disk & USB key and open Disk Utility
In Disk Utility, click on the OS Disk and then click on the ‘New Image’ icon at the top of the window, pick a name and save it to your Desktop
Once the image is created it will appear in the left hand window of Disk Utility, click on it and then click on ‘Images’ in the menu bar at the top of the screen and choose ‘Scan Image for Restore’
Once that has verified your image, click on your USB key in the left hand window and and choose the ‘Restore’ tab in the main window.
Next drag the image you created to the ‘Source’ field and drag the USB key to the ‘Destination’ field, tick the box that says ‘Erase Destination’ and click on ‘Restore’.
This will erase your USB key and replace it with the contents of your image, so all of the files on the OS disk will be transferred to the USB key, with the end result being a bootable USB key
Once this has completed, eject the USB key and plug it in to your MacBook Air and hold down the ALT key whilst powering it on, you should be presented with the option to boot from the hard drive or the USB key, if you have set a firmware password though you will need to enter this to gain access to the boot menu
When you have booted from the USB key it will vary depending on which OS you have created it from, but usually you will have to agree to a license agreement to get to the pre installation screen, at the top of the screen you should see a Utilities menu, you must click on this and run Disk Utility.
When you are in Disk Utility click on the hard drive you wish to erase, then click on the erase tab, you can then choose which type of deletion you require, I would choose the highest security option, which involves multiple passes of the hard drive, but this can take several days depending on hard drive size, if you don’t have the time then choose a lower security option, but remember more secure = many hours = less chance of data being recovered.
If your Mac is running slow, there is a chance that you could be suffering from Directory Corruption, to find out if you are the you will need to do the following
If all is well then it will tell you with the following notification
Verifying volume “Macintosh HD”
Checking file systemPerforming live verification.
Checking Journaled HFS Plus volume.
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Checking volume bitmap.
Checking volume information.
The volume Macintosh HD appears to be OK.
If you get any other message, usually in red, then you will need to repair your disk, you can’t normally do this from within the Operating System, so you will need to boot from an external device, or if you are running lion then you can boot to the Recovery HD
Once you have booted from another drive you will have the option of running Repair Disk on the affected drive
If it still cannot repair the corruption then you will need to use another utility, I’d recommend DiskWarrior, it’s just under $100 but it can be invaluable in recovering a system affected by corruption, and if you were to take it into a shop then they would probably charge you more than that to resolve this anyway.
This uses a different method of repair by collecting data from the system and rebuilding the directory structure, there are warnings that it could result in data loss, and as with any kind of system repair there is always a risk of some data being lost, but I have used this program 12 times over the past 8 years and its worked 100%.
This is the most simple of maintenance tasks and one of the most overlooked, many people will take their machines to shops as they believe their machine has a serious problem, which can usually be fixed by this one task.
To do a permissions repair you have 2 options, using the Disk Utility app (recommended for most users), or using the command line, which is just as easy, but some people may not be that comfortable doing it this way.
So first, I’ll go through the Disk Utility method, this application is located in /Applications/Utilities
Double click on the application to start it up, now on the left hand side you will have a list of drives connected to your machine currently, on a MacBook Air you may only have your main hard drive listed, on a Mac Pro you may have several hard drives, a couple of SuperDrives, maybe some external USB drives etc.
The one you want to focus on is your system drive, this is usually the top one, but you want to click on the Volume, not the actual hard drive, the volume is usually just underneath with the same hard drive icon, but slightly indented from the edge, on a standard Apple installation this will be called Macintosh HD but it can be named anything.
This will chug away for a while, if you do this regularly then it will only take a few minutes, but if you have never done it then it could take many hours.
Once done I’d recommend rebooting your machine and you should notice an improvement in performance, the reason for rebooting afterwards is I’ve found that quite often some applications or services that had issues starting up before the permissions repair
will end up in some sort of crashed state, so the repair won’t appear to have resolved anything, rebooting causes all of these items to restart and as they should now have the correct permissions and will be able to run correctly, thus not crashing, and not causing a system slowdown
Next I will run through the command line guide to this.
Open Terminal which is located in /Applications/Utilities
sudo diskutil repairPermissions /
this will prompt you for your admin password and will again chug away until done, you will recieve a better idea of its progress as it has a progress bar with a percentage completed, which the GUI option doesn’t have
All thats left to say is make sure you do this regularly, After every major software update or installation should be fine
I have done a video running through a Repair Permissions here