Recovering data from an Apple RAID using Data Rescue 3 by Prosoft Engineering
16 Aug 2011
Data Rescue 3 has an Add RAID Set which allows you to simulate a RAID configuration based on the RAID functionality built into Mac OS X. This is helpful in case an Apple RAID configuration fails to mount or be recognized as a single volume. Please note that Add RAID Set does not attempt to fix or repair a RAID set. Instead, the RAID set is configured through Data Rescue for the purpose of scanning for data.
Once the RAID set has been added, it can be selected to scan for data. In some cases, data may not be opened properly when recovered if the hard drives are not arranged in the correct order.
If data is not being recovered properly from the RAID, we suggest the following steps to troubleshoot the issue:
- Adjust the allocation block layout and reattempt the recovery until all options are exhausted or files are recovered.
- Redefine the RAID Set by using Add RAID Set, and drag to rearrange the order of the hard drives / volumes. Data Rescue does not currently support editing an existing RAID set. To change the configuration, you must define a new RAID Set using the different parameters.
Data Rescue 3 supports 3 basic types of RAID, described very briefly below.
Stripe – This is also known as RAID-0. As data is read sequentially from the RAID set, it comes first from the first component drive until a stripe-sized amount has been read, then the next data comes from the second component drive, and so on, in round-robin fashion.Mirror – This is also known as RAID-1. With this scheme, each of the drives is suppose to contain the exact same copy of data. This means that if you have an undamaged component drive, you should be able to just scan that to find your files (you will not need to create a RAID set).Concatenated – This is not an official RAID level, but rather a way to make multiple hard drives appear as one big drive by concatenating them together. As data is read sequentially from the RAID set, it comes first from the first component drive, until the end of that drive is reached, then continues coming from the second component drive, and so on until the end of the last component drive.
The ordering of the component drives is mainly important for stripe and concatenated types. If this is wrong, the scan may find few or no good files. To alter the order, simply drag each drive in the list into its proper position.
Adding RAID Sets
Data Rescue 3 demo link: http://s3.amazonaws.com/prosoft-engineering/drmac/Data_Rescue_3.2_US.dmg
To simulate RAID configurations in Data Rescue 3, please follow these steps:
1) Go to the “Data Rescue 3″ menu at the top of the screen and select “Preferences”.
2) Click on the check box for “Enable Expert Features”, then close the Preferences window.
3) Ensure you are within the “Detail View” for Step 1 to see the list of devices. If you are in Arena View (with the animated interface) click on the “Detail View” on the bottom left corner to change views.
4) Hold the “Command” key and click on the Devices that belong to the RAID set. This should highlight multiple selections.
5) Click on the “Expert” menu at the top of the screen and select “Add RAID Set”.
6) In the RAID panel, rearrange the order of the drives accordingly from first device to last.
7) Select the type of RAID the set was (Stripe, Mirrored, Concatenated). Select the RAID Stripe Size if you know this information. If you are not using a Striped RAID, leave the Stripe Size as 32K. Click on “Continue” when done.
8) You will notice a new drive to scan in your list as “RAID SET 1″. You may select this as your drive to scan. Proceed with selecting your scan method to search for your files.
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