Your RAID array has collapsed. The data seems to be gone and you are struggling with what to do next. Your RAID is supposed to have fault tolerance, it shouldn’t lose data. How can this be? Well, there are a number of reasons why and how RAID implementations can fail, and if that happens, the only thing to do is to look at careful RAID recovery.
You, or a RAID Recovery Professional?
If you are not experienced with RAID recovery and you don’t really understand how it works, then you shouldn’t be trying to rebuild your system. You may make a mistake that could lead to very serious problems and a complete loss of all your information.
In most cases, you should contact a professional who can not only fix the array components, but ensure that the data on it is not lost and can easily be recovered. The RAID recovery process will cost you money, but we would consider that as good investment that comes with peace of mind.
RAID Recovery DIY
If you feel comfortable enough to have the RAID recovery done by yourself, then the steps to do so are the following:
- First, you need to determine and secure the physical aspects of your RAID configuration. This is done by labeling the hard drives, cables, ports etc.
- Disconnect all member disks and connect them to a controller that is able to work with each separate disk individually. This can be a non-RAID controller, but it can also be a RAID-controller that is set to operate in single drive mode.
- Using specialized software, which can be found online at a number of sites for RAID recovery, you will be able to recover the parameters of the array.
- If the software allows you to rebuild the RAID without the need to initialize it, then you can try to build the system in that mode based on the parameters determined by the software. It is very important that you are careful here, because if you attempt to rebuild the RAID in the wrong order, you will lose the data on it and your entire array will initialize with zeros.
- If it is a hardware RAID, you can load the array contents into the software and then mount the disk in the operating system. If you have a software RAID, you need to use data recovery software that can create an array image file.
- Once the data is saved, you can proceed to rebuild the physical parts of your RAID configuration and restore the data.
Determining RAID Disk Order
You need to determine the disk order before attempting a RAID recovery. You can do this by looking at the log files paying close attention to events and related time stamps. You can also use a hard drive viewer tool like WinHex to determine the disk order. When a fragment is found on one member disk, it will track what disk contained the fragment and so on.
To determine the first disk, you use the drive view tool to search for MBR in case of hardware RAID, since the MBR is found on RAID 0. For software RAID 0, you need to search for the boot sector.
Going through a RAID recovery process after the RAID failure is not a fun thing. You need to spend a lot of time rebuilding so that you don’t lose any data. Then you have the worry that it may fail again. While RAID failures are rare, they do happen and you should always make sure you have up-to-date backups just in case it does happen.
Chance favors the prepared mind, so you need to prepare for the worst. When it happens and you are forced to do a RAID recovery, you won’t have to spend as much time worrying about the information itself, and you can spend more time recovering and rebuilding the physical configuration and parts of your RAID.