How to migrate a raid array from regular disk to mirror?

Question

QUESTION: Can I set up Mirror without deleting first drive?  I have a Power Edge 860. It has a Dell SAS 5 (6.12.05.00 ) SAS 1068 Card in it.  I have never set up Raid on this computer but am going to do it now. I’m going to set up Mirroring of two drives.  I’m  confused by the software and the pdf help. I have set up my OS etc. on the first drive, which is now just a 'regular' drive with windows 2003 on it. (it is not raided yet.)  If I want to now make this working system into a RAID mirror do I have to blow away the original drive and reinstall or restore from BU. It seems to say here and there that I can migrate but the software is in my opinion kind of cryptic on the topic. I don’t want to go any further, unless I’m sure that it is going to keep the first drive and just mirror over the data.  Here is where I’m at. I boot into the SAS bios Choose the Adapter and then go into the RAID Properties, then choose Create IM, and then get to the Create a new array screen,  I Move the cursor to the RAID Disk column and select a disk. I change the NO to a Yes by pressing the + key or space bar. I then get a message saying  *** Warning !  Data was found on the selected disk. This data will be lost when the array is crated. *** Choose discard configuration or Cancel Exit on the next screen to abort.  This is where Im stuck. In the following document it says... http://www.lsi.com/downloads/Public/SATASAS%20HBAs/SATASAS%20HBAs%20Common%20Files/IR-SAS_UserGuide.pdf .. that if this is the first disk you will be prompted if you want to overwrite existing data. However when I do press the + I get the message above. The document says I should press M at this point if I want to save the data on my first disk.(I think M is for migrate.) However the bios software doesnt say anything about M for migrate.  It doesn’t say anything. I don’t want to continue as I frightened that its going to delete the data on the first drive, based on the warning it gave me previously.  Does anyone know if I can migrate and if Im doing it right. I mean the warning seems clear  Warning !  Data was found on the selected disk. This data will be lost when the array is crated.  Choose discard configuration or Cancel Exit on the next screen to abort.  Regards   Dazed and confused.

Daniel My · Accepted Answer

Hello Col288

The short answer is that you will need to backup, create the array, install the OS, and then restore from backup.

What you are wanting to do is reconfigure fron a non-raid configuration to a RAID 1. Our SAS controllers do not have the option to reconfigure. What you are attempting to do by just creating a RAID 1 with a drive that has existing data and a blank drive is called a retag. This is not supported, but may work on one of our PERC controllers that have the option of whether or not to initialize the drives after an array is created, but the SAS controllers autoinitialize after the array is created. The process of initializing the drives is destructive and will wipe the data.

If you were using a PERC controller you could create a RAID 1, choose not to initialize, force the blank drive offline, boot up the server, and then reseat the blank drive to let it rebuild. This is not an option with the SAS controller because of the forced initialization though. I hope that cleared it up a little bit.

Thanks

theflash1932 · Answer

The SAS 5/6 supports non-RAID or RAID, but they are not compatible or interchangeable. Moving from a non-RAID configuration to a RAID configuration (or vice versa) will cause the existing data to be overwritten 1) by RAID settings and other metadata, and 2) as part of the automatic initialization of the array/disks for use in a RAID configuration.

A retag is not necessary (and not wise) on a PERC 5/6 controller in this type of scenario: The PERC does not support non-RAID, so any single drive in the system must have been configured as a RAID 0, which CAN be converted (reconfigured) to a two-disk RAID1 ... on the fly, while online.

col288 · Answer

Thanks its not a pleasant answer (not your fault) but it is the truth. I have followed your advice. Backed up, put in two new drives, restored from backup (love paragon backup CD) and up and running . Took all of about 1/2 an hour.

Thanks.

theflash1932 · Answer

Glad things when smoothly (and fast!).

PowerEdge HDD/SCSI/RAID

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