# Rebuilding RAID 1

## BdON

Hi,

I just built a RAID 1 array for file storage purposes.  It is fake raid and I used the Intel Matrix RAID utility on my motherboard to build it.  I strictly used dmraid to then patrition/format in Linux.  One of the hard drives seems to be bad so I am going to RMA it for a new one.  When I get my new one, how to I go about rebuilding from the data on my good drive?  Intel's site gives instructions for Windows but I don't have it installed.  Does anyone have experience with this, will it rebuild itself?  Thanks

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## magic919

I don't think dmraid can do that.  Can you do it in the BIOS?

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## devilheart

bios raid utility should do it

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## cyrillic

 *BdON wrote:*   

> Intel's site gives instructions for Windows but I don't have it installed. 

 

That is strange.  I thought the only reason for running dmraid is to maintain Windows compatibility.

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## BdON

 *cyrillic wrote:*   

>  *BdON wrote:*   Intel's site gives instructions for Windows but I don't have it installed.  
> 
> That is strange.  I thought the only reason for running dmraid is to maintain Windows compatibility.

 

I have not had any experience with raid/dmraid before and the only good guide I could find used dmraid.  Now that I've read a little more I believe it would be wise to go with software raid as opposed to a fake raid.  For this, I would be using mdadm, correct?  Does anyone have a link to a guide for me?

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## devilheart

you can try with this http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml

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## energyman76b

why are you using bios-fakeraid anyway?

linux software raid (md+mdadm) is easy to set up and much less troublesome.

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## DirtyHairy

I found http://linux-raid.osdl.org/index.php/Linux_Raid helpful...

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## energyman76b

http://en.gentoo-wiki.com/wiki/RAID/Software

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## salahx

Unfortunately. dmraid can assemble a healthy RAID (it just reads the metadata on the disks and sets up the device mapper appropriately - it doesn't even need the correct disk controller), that is the currently the limits of its abilities. It cannot repair, reshape, or write metadata - which is necessary to rebuild a degraded RAID array. You'll have to use the Windows utility to rebuild the degraded array. 

The last message on atariad-list about isw rebuild support is https://www.redhat.com/archives/ataraid-list/2008-September/msg00000.html , which was over 4 months ago. So if you don;t have Windows on your machine, you might want to swtich to md.

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## minor_prophets

I have 2 raid machines.  One using DM and the other lvm.

I have to say, despite many others being down on lvm, the only difficulty I had with it was the initial setup.  I weathered several stumbling blocks and prevailed.

raid1 on dm Athlon XP

mixed raid 1 and 0 on lvm Athlon 64

lvm seems to be to quite flexible and fast.

One more thing.  Emerge smartmontools if you haven't already and follow the guide(s) making sure SMART is turned on in those hard drives.  The tri-weekly email notifications give me some piece of mind.  Oh, and if you don't have one already, buy a UPS.  I view that as the biggest RAID1 data integrity protector.

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## salahx

It appears I must rescind the remark about dmraid not doing "repair, reshape, or write metadata": https://www.redhat.com/archives/ataraid-list/2009-January/msg00014.html

Apparently is been in CVS for at least 7 months.

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