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How to break mirror disk in linux?

Jayanth Kamatala
Occasional Visitor

How to break mirror disk in linux?


I have a HP Proliant DL385 G5 server with two 250 GB disks. I have installed RHEL 5 on it. While partitioning it just showed me one disk; and I have carried on the installation with it. After Installation, I figured out that the 2nd disk is a mirror for the OS and I can't see it thru fdisk.

Now, I want to make use of the 2nd disk by partitioning it. How do I do it? It doesn't even show up in fdisk?

Any help is appreciated..!

Michal Kapalka (mikap)
Honored Contributor

Re: How to break mirror disk in linux?


you have raid 1 ( mirror ) configured on the raod controller, this is the rerason why you are see only one disk for the OS, if you like to break mirror, you need to go to ACU,
and the delete the raid, and make 2x single disk RAID1. But this will remove all data from the disk.

The best way is to buy aditional disks and create a second raid1/5.

Honored Contributor

Re: How to break mirror disk in linux?

You have a SmartArray hardware RAID controller. With two disks, it probably auto-configured a RAID 1+0 (with two disks this is equivalent to RAID 1, but expandable) array for you when the system was installed.

To change your disk configuration, you'll need the SmartArray configuration tools (hpacucli or cpqacuxe RPMs). These tools are included in the SmartStart CD, in the Proliant Support Pack, or you can install them separately from too.

See this whitepaper about the procedure for breaking the existing RAID 1 array:
I would recommend the procedure on page 3: Splitting a mirrored array using the Array Configuration Utility. You'll need the SmartStart CD for this: the server must be offline to split the array.

The splitting procedure will make the 2nd disk visible to the OS as an independent unit, although it will originally have a complete copy of the contents of the system disk. You can then re-partition and use it as usual.

To better understand the SmartArray configuration and the tools to manipulate it, please read the SmartArray configuration reference. It might be useful for the future: