Help with Restoring Raid 1 Disks

[Malam]

I had two drives setup as a Raid 1 Using the Marvell Chip on my ASUS P6X58 Motherboard. The Raid system worked fine with no problems until this morning. I had to re-install Windows 7 and after the install, I thought all I had to do was reconnect the Raid drives. Windows is reporting the drives as "Failed" Mirrored disks. Looks like I am missing a step or two, but don't know what to do. Thanks for your help.

[supaflyx3]

did you initialize the drives in your bios and make sure they say the array is fine?

[Malam]

Originally Posted by supaflyx3

did you initialize the drives in your bios and make sure they say the array is fine?

A ha..no. I think I have to install the Intel Matrix Storage Manager. Will do and provide an update later. Thanks.

Just check again .. I installed the Intel matrix Manager only to find that I do not need the driver since my Raid set was created with the disks connected to the Marvell Chip. I believe the Raid Set was created threough the Windows Disk Manager. The two drives are shown by the Windows Disk Manager as "failed". But I did not do anything other than to reinstall the OS ! Did that nullyfies the Raid Set ?

[Malam]

I could not get the Raid set back. I recovered the data from an external backup that I have. I need a better understanding of the way software and hardware Raid works and perhaps what to do in case I need to re-install the OS again. Any ideas where to look ? Thanks.

[NyteOwl]

At their most basic, RAID works in principal the same way whether it is hardware based or software based. The main difference being all the processing required for compression, parity calculation (encryption if any), drive cueing and such are handled in silicon, offloading those chores from the CPU and providing a noticeable speed improvement at the same time.

"Fake-RAID" is a combination of on chip BIOS instructions and OS drivers that do fundamentally the same thing as a hardware RAID controller but far more cheaply and somewhat slower.

Software RAID does all the operations in software using the CPU to do any needed calculations. Again it does the same fundamentals but more slowly.

The tradeoffs are simple:

1) hardware RAID is fast but costly. Drives configured using one RAID controller generally only function as intended when connected to a controlelr of the same type.
2) fake-RAID is moderately speedy and fairly inexpensive but is more resource hungry and usually quite proprietary to the motherboard or controller card used. Moving disks from one fake-RAID system to another often does not work.
3) software RAID is the slowest option but has the benefot of being very transportable between machines so long as the same OS is in use.

RAID 1 is the simplest form of RAID (disk mirroring). Generally all that you need to do to restore an array (so long as you have one good disk) is to remove the defunct drive, add a new one of equal or greater size (formatting if necessary to the RAID system you're using), add the drive to the array and the RAID hardware and/or software should rebuild the array by creating a copy of the functioning drive to the new one.

If both drives have failed of course the array is irretrievable and must be recreated from scratch.

There are many descritpions on-lien of the various forms of RAID and how they work. A decent set of visual tutorials on the most common RAID levels can be found at JetStor - Visualize Your RAID

Hope it helps some.

[Malam]

Thanks for a very detailed post, its appreciated. I am leaning towards getting a hardware raid solution because of its indepence from the OS. From your explaination, even if the OS is corrupted or needed to be re-installed or upgraded, the hardware raid array is not affected. The one main variable is the raid controller. One question that I still have though is that if you have a raid array (Raid 1), can the disks be read by windows if they are removed from the array ? Thanks.