RAID 1 with 2 different drives

[thebennyboy]

I currently have a Seagate Barracuda 3TB, the one with a monstrously high failure rate. If i bought another 3TB drive from another manufacturer can i still create a RAID1 array?

Also is it possible to create a RAID1 array without any data loss on the existing drive? Want a bit of redundancy if the Seagate drive fails, which scares me a lot as i have about 1.5TB of videos, music and games on it.

 

[ED209]

you can use different make HDDs and should be fine.

I don't think you can create a raid 1 setup without loosing data as it needs to format the disks for raid use(I maybe wrong as my knowledge of raid setup is limited)

 

[Greebo]

99.9% certain it will wipe the date on the existing drive as it needs to alter the partitions and write extra data.

However it can be done like most things on the pc but isnt easy!

1. Know where the RAID signature is written

It can be found experimentally by writing a known pattern to the disk, creating RAID in BIOS, and checking where the pattern got overwritten. This information can also be found on the net, in dmraid (http://people.redhat.com/heinzm/sw/dmraid/) program sources, in various documentation, but beware - that information may be incorrect or outdated.

2. Make space for the RAID signature

Move or shrink the partition which is overlapping the RAID signature.

3. Clone the drive

Clone sector-by-sector using something like dd (http://en.wikipedia.org/wiki/Dd_(Unix)).

This step may be unnecessary, but it usually is, because:

- dmraid does not sync the mirror
- many BIOSes don't do it either
- if they do, it may not be easy to determine the direction
- some BIOSes allow to create degraded array, but many do not

4. Write RAID signature to both drives

Can be done using dmraid (http://people.redhat.com/heinzm/sw/dmraid/), but its write support is limited, last I checked it still could only write Intel signature format.

Can be done by creating RAID in BIOS, but beware! - BIOSes often not only write the signature, but also overwrite other parts of the disk, for example overwrite first 1MB of the disk with zeros. The experiment from step 1 may provide information about what gets overwritten. The overwritten data has to be backed up and restored.

5. Make Windows boot with the RAID controller enabled

Since Vista automatic repair from the DVD can often make the OS bootable.

If automatic repair can't fix it, or is not available (XP/2000), it can be fixed manually.

There are 3 pieces to the puzzle:

a) a driver file in %SystemRoot%\system32\drivers
b) a service entry in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\, creating a service for the driver file
c) an entry in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\CriticalDeviceDatabase, assigning controller ID to the service

Copying the driver file is easy, but creating the registry entries is enough material to write a whole new post about it.