How To Recover The System When Mirror Disk 0 Fails

[cngarcia]

Hi,

 

Recently I installed a couple servers in Windows 2008 R2 (no sweat). I also established disk mirroring in both servers (no sweat either). But I began to think about what to do i case of disaster, so I build a test server to simulate disk failures. I found that if disk 1 fails it is very easy to recover (just install a new disk 1 and re-establish the mirror). BUT if this disk 0 is the one that fails it's another story.

I have tried different ideas, searched TechNet, searched Internet and I did not find a solution to this theoretical but possible problem.

 

Can anyone give me an step-by-step solution to this problem?

 

Regards,

 

CNGarcia

[ICTCity]

Hi,

 

In a RAID1 environment (or MIRRORING) you can support just ONE disk failure... no matter if it is disk 0 or 1.

 

If the disk is the "primary", your system will still be able to do everything, but, in order to rebuild the array, you must do the following:

 

Create an image of your system, delete the array, rebuild it, restore the image.

 

There are controllers which can create a RAID 5 from a RAID1 (also if broken).

 

You can also (but you must do it BEFORE the disaster) implement a RAID 1 with parity (3 disks), this will prevent the "restore" of the image in case of a failure on disk 0.

[cngarcia]

Hi,

 

Thanks for your help. First, I my test I am assuming that one and only one disk is failing. Second, when disk 1 fails I am able to replace the disk and rebuild the array I have no problem at all powering-up the system with disk 0. The problems comes when I try to simulate disk 0 failure. I can boot the system from plex 1 but I cannot replace the disk 0. If I replace the "bad" disk 0 and replace it by a blank new disk the system try to boot from this disk, and obviously it has no system yet, so the system won't boot. If I physically switch disk 1 to disk 0 the system boots but with a message saying that my Windows is an illegal copy.

Now, you say that I must create a system image. By this, you mean a full system backup or just a boot disk? I try to find a way to create a CD (or DVD) boot disk with no luck. If you mean a full backup then I'm a little bit disappointed with the mirrors because the idea of the mirror is to have the system up and running very quickly.

Is there a tutorial explaining the procedure? I saw the in your site there is a tutorials section.

 

Again, thanks for your help.

 

Regards.

[ICTCity]

Raid 1 is useful but not the best solution.

 

The point is everytime the same... people confuse HA with DR. Raid 1 provide a COPY of disk, so you can access your disk (even if one is failed), but this doesn't mean you can keep working without problems.

 

One your system is up and running, I usually take a full backup for the entire system. Then, day per day, a normal backup. In case of a disaster, you can rebuild your array (as described in previous post) from the image.

 

I know this is disappointing, That's because I rely on RAID5 instead of RAID1 (which actually is the same process of raid one in some way, but it can rebuild everything from just 2 disks, there's no principal disk).

[cngarcia]

Thank you for the illumination. I think I should go for plan 'B'. You are very kind.

[ICTCity]

If you want to continue / share your ideas, feel free to do it.

 

I'm really interested in this topic. I can't find people which are really interested in discovery how things work, just "use and wait until disaster".

 

If you want... I'm here :)