Perc 6/E Foreign Configuration Lost - Please Advise

Hello Mark

Before I advise on how to possibly get the array back online I'm going to give a disclaimer. If the data is important then you should contact a data recovery company. Any attempts to recover the data could further corrupt it and make it more difficult or impossible to recover.

Let me explain what the situation is before I tell you how to possibly fix it. The array information is stored in the controller cache and on the hard drives themselves. When that information does not match between the controller and hard drives the controller will put the array into a foreign status. This helps prevent data corruption. When this happens you have two options, you can import the foreign configuration or clear it. If you import the controller will rewrite the configuration it has stored with the configuration stored on the drives. If you clear it then it deletes the metadata tags that define the array off of the hard drives. Clearing the foreign configuration is the same as deleting an array.

The good thing is that deleting the array only deletes the metadata tags that defines the array. It does not actually delete the data or array formatting off of the drives. Because of this you can do what is called retagging. Retagging is when you create the exact same array. If the metadata tags are rewritten to the drives then it make the data accessible again. The trick is to make sure you have the exact same settings as the previous array. If the array is created with a different number of drives, different stripe segment size, or a different array size then the data will not be in the expected location. If that happens it will discard the old array formatting and write new.

Here is the process to retag your array:

1. Create a new RAID 6 using drives 0-5 just like the old array had
2. Be sure to use the same stripe segment size and space as before
3. Be sure to NOT initialize the array. It will recommend that you do. Be sure to NOT do it. An initialization is an array data format(Destructive to data).
4. Before you exit the controller BIOS be sure to offline drives 0 and 5. If you don't offline those drives then it will sync the array using those drives. Since those drives are essentially blank it will wipe all of the data if they are online when the array is booted.

Once that is done you should have a RAID 6 created with drives 0-5, and drives 0/5 should be offline. At this point you should try to boot up and access the data. If the data is available back up before trying to rebuild 0/6 back into the array. I would suggest that you have a backup solution ready before you start doing any of this.

After you have the data backed up I would recommend that you delete the array, create a dissimilar array, then recreate the array you want to use. I would not recommend that you continue using this array. Retagging is an array recovery procedure that is used to get access to data. It should not be seen as a permanent solution. Also, because there was discarded cache there is likely corrupt array information. In short, you will likely have problems with this array at some point in the future. That could be 2 minutes after the retag or never.

The reason you want to create a dissimilar array is because if you don't you are just retagging. The controller may not rewrite the array data, and you may encounter corrupted array data in the future because of this. Create a 6 drive RAID 0 or anything else that is not the same array you are currently using. Then initialize the array. After that completes delete the array, create the desired array, and initialize again.

Good luck

Great answer Daniel.

Saves me from a backup recovery, that maybe took me 2 or more days.

The only thing that i missed in your post are the posible reasons for this problem.

Regards

I have a RAID 1 VD0 that is fine.  I had noticed the D: drive (VD1) had gone missing, but the data was not important.  It consists of a single 3TB disk.  I had to shutdown and reboot for a move and then now have "FOREIGN" assigned to the VD1 but I do not care about the data on VD1 (D: drive) and just want to reboot from the good VD0 (C:).  I cannot figure out what option to take (import or clear).  I am pretty sure that the single 3TB disk is bad and I can easily replace it, but not sure of the correct steps.

Thank you very much, Daniel.

Please, do not follow instructions in manual to clear foreign configuration; it actually led you to clear VD configuration.

I followed your instructions in a PowerEdge 2900 Raid 10 cleared and Disk 5 out of order.

Then started Windows 2003 server normally.