RAID 1 – Can a Single Disk RAID 1 Array Be Built?

raid-1

I have an Nvidia hardware RAID 1 array and need to reformat. But I don't have any spare storage media, so I need to get along with the 2 disks in the array. I figured I'd do as follows:

Delete the array, so I have 2 separate but identical disks, A and B, with my files
Put disk B aside
Reformat disk A, build RAID 1 array with it, install Windows XP
Put disk B back in
Boot to Windows on disk A, copy my files from disk B to disk A
Add disk B to the RAID 1 array, rebuild array

And now I'd have a new RAID 1 array, fresh install and all my files intact (the ones I copied). Here are the parts I'm unsure about:

Can I build a RAID 1 array using just one disk, then add the other one later?
Can Windows on disk A see disk B and allow me to copy my files over?

Best Answer

I don't think you would be able to build a degraded (only one disk) raid array. Best plan is to copy the contents of disk B to some removable media (Ext HDD, flash drive, DVD's if you have to) build the array with both disks, copy the files over from the removable media.

Related Solutions

Can a mirrored (RAID-1) disk be plugged into another system to be read

regardless of any controller/driver

Disregarding RAID implementation? Then the answer should generally be no: you can not assume that all hardware controllers treat disks in such a transparent way.

However, in the case of software raid in Linux (md+raid1) then yes, there's no disk header or secret block-level optimization going on there.

In the case of Disk Mirroring in Windows, it involves the disk having been initialized as "Dynamic" and, well, should just work, given that the system that reads it can understand the dynamic volumes - in other word it will most likely only be accessible from another system running Windows.

In the end; you can try connecting the disk regardless of controller. If it works, it works. No controller will damage the data on the disk as long as you don't tell it to - i.e. as long as you don't execute an operation such as "initialize" or anything.

Ubuntu 12.04 – Add RAID 1 Array on existing device

Create a new RAID1 array with a "missing" device using the following in a terminal (may have to employ the sudo command):

# mdadm --create /dev/md0 -n 2 -l 1 /dev/sda1 missing

You'll be able to move all the data onto /dev/md0, boot with that, then add /dev/hdb1 into the mirror:

# mdadm --manage /dev/md0 -a /dev/hdb1

Backup your data first and get familiar with mdadm and software RAID on Linux to avoid shooting yourself in the foot.

Best Answer

Related Solutions

Can a mirrored (RAID-1) disk be plugged into another system to be read

Ubuntu 12.04 – Add RAID 1 Array on existing device

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