Mirrored & Stripped Raid Sets Made easy

Jan 19
18:38

2012

Derek C Wicks

Derek C Wicks

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This article guides one through the process of creating both mirrored and stripped raid sets on your Mac OSX. Step by step this article instructs you how to create the disk images and how to merge them.

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Over the past weekend I had a friend ask me to set up a back-up drive for them to protect their essential data. They wanted me to set up a traditional Time Machine disk to mirror their start-up disk. I suggested a mirrored Raid set using the Apple supplied Disk Utility that came with their OS. Setting up a mirrored drive is quite simple with Disk Utility and creates a complete back up of the drive that it is mirroring. A mirrored raid set up,Mirrored & Stripped Raid Sets Made easy Articles or otherwise known as Raid Level 1, is quite simple to set up. These steps should be preformed by a knowledgeable technician and your data should always be backed up. MAKE A TIME MACHINE BACKUP before you attempt these steps or before you attempt any changes or alterations to your startup disk or Mac OS. Further details on Raid arrays can be found on the apple.com site under 'support'.

Here are the steps: Raid 1 - Mirrored Raid Set

1. Open Disk Utility found in Application/Utilities/Disk Utility

2. In the left hand column select the disk you would like to mirror and click RAID.

3. Give your Raid a name, select the format you would like to use and set Raid type to Mirrored Raid Set. Then click the add '+' button.

4. Highlight the Raid array you just added and click 'Options'. In the dialog box set the block size you want to use (I suggest 32k as a general size). You must decide if you want your Raid set to 'automatically rebuild itself', I suggest you do select this option.

5. Once you have made your selections in 'Options' click OK and your Raid set is ready to add the drives you want to use in your Raid.

6. From the left hand side of the Disk Utility panel select a drive to add to the Raid and drag it over the new Raid array you just created. The drive or 'Slice' will be added to the Raid set. Add a minimum of two drives to your array.

7. Click the 'Create' Button. A warning window will remind you that all data on the drives added will be erased and all data lost permanently. Click 'Create' to create your Raid set Level 1 drive. Disk Utility will format the Raid slices and rename the added slices to create a new drive then mount this drive on the desktop.

You have now created a mirrored Raid 1 set.

For those of you that have a need for larger drive space and faster write times to your drive you can create what is known as a Striped Raid Set or Raid Level 0. The steps are the same with the exception that you are selecting 'Striped Raid Set' as your Raid type.

So lets say you have four drives 750 gigs each and you want to make two Striped Raid Sets 1.4 TB big and Mirror the sets. So how do you make a 'Mirrored Striped Set' or Raid 10? The process is very simple and straight forward.

Create Raid 10 - Mirrored Striped Set

1. Create two Striped Raid Sets, name one 'Set1' and the other 'Set2'. You now have two drive images each 1.4 TB on the left hand side of the Disk Utility window (each set will show the two drives or slices that make the Raid set).

2. Create a third Raid set, this time make the set a Mirrored Raid Set and name the array 'Macintosh HD'. Once you have clicked the '+' button and your Raid array is displayed in the lower right of the Disk Utility window you can added the components of the mirror.

3. Drag both Set 1 and Set 2 disk images from the left side of the Disk Utility window over the 'Macintosh HD' Raid array on the right to add these two Striped drives to the mirror.

4. Click 'Create' and the warning window will advise that all data will be lost, click 'Create'. Once Disk Utility has created the Mirrored Striped Set disk you will see a new disk image on the left side of the Disk Utility window named 'Macintosh HD'. Your Raid 10 has been created.

What does a Raid 10 give us? First it lets you combine multiple drives to create a mega drive (Striping). We then can create an exact copy of everything on that mega drive by Mirroring the drive. This gives us large storage drives and the security that our data is backed up and secure. If 'Set 1' becomes corrupt your Mac will use 'Set 2' automatically. Set 2 is of course an exact 'mirror' copy of Set 1. When information is written to Set 1 the identical information is written to Set 2.