LinuxQuestions.org
LinuxAnswers - the LQ Linux tutorial section.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Hardware
User Name
Password
Linux - Hardware This forum is for Hardware issues.
Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

Notices

Reply
 
Search this Thread
Old 03-17-2007, 09:08 PM   #1
Kvetch
Member
 
Registered: Mar 2004
Posts: 35

Rep: Reputation: 15
Sata Raid 1 and Single Sata drive drive order issue


Hello, I am having some issues getting my system (Epox 9npa+ultra with nvidia raid) to see my drives in the right order. I have a single SATA drive and now I recently purchased two new sata drives. I set them up in a raid 1 mirror. The single drive is connected to the first sata connection and then the other two on sata connections 3 & 4. For some reason when I boot into Linux (Gentoo) it sees the RAID mirror as the first scsi device and not the single sata as it use to. So fdisk -l shows the raid is now sda and sdb and the single is sdc. I am not sure why it is seeing the raid as separate drives either. I thought it would only see one drive.
Anybody have any clues as to how I can get the raid to be lower on the scsi chain than the single drive and why does it show them as separate drives?

Thanks,
Nick
 
Old 03-17-2007, 09:11 PM   #2
Quakeboy02
Senior Member
 
Registered: Nov 2006
Distribution: Debian Squeeze 2.6.32.9 SMP AMD64
Posts: 3,237

Rep: Reputation: 121Reputation: 121
Some of your questions are answered here:

http://linux-ata.org/faq-sata-raid.html
 
Old 03-18-2007, 09:54 AM   #3
Kvetch
Member
 
Registered: Mar 2004
Posts: 35

Original Poster
Rep: Reputation: 15
Thanks Quakeboy, I saw another post talking about dmraid but I was really hoping I wouldn't have to use it.
 
Old 03-18-2007, 03:55 PM   #4
Kvetch
Member
 
Registered: Mar 2004
Posts: 35

Original Poster
Rep: Reputation: 15
Since this is not going to be my primary drive and I do not dual boot would it just be better to use the kernel's software raid?
 
Old 03-18-2007, 04:11 PM   #5
Quakeboy02
Senior Member
 
Registered: Nov 2006
Distribution: Debian Squeeze 2.6.32.9 SMP AMD64
Posts: 3,237

Rep: Reputation: 121Reputation: 121
"Since this is not going to be my primary drive and I do not dual boot would it just be better to use the kernel's software raid?"

Ah, I see the confusion. DMRAID uses the kernel's software raid. I've given this before, but here is a simplified version of how Linux used FakeRaid devices.

First off, the case where you're booting from a FakeRaid. The BIOS uses the code in the FakeRaid to read the data off the disks in proper order so that you can boot. During Linux boot, at some point the kernel is loaded to memory and needs to take control of the disk drives - this is true whether it's an IDE disk, an ATAPI DVD/CD, or a FakeRaid. In the case of FakeRaid, the DMRAID software reads what is called metadata from the first device in the array. It uses this to figure out whether the data is striped or mirrored, and configures kernel access, accordingly, and Linux goes merrily along its way.

In the case of not booting from the array, then the kernel once again uses DMRAID to read the metadata and configure access to the array. But, either way, the configuration entails using the kernel's "software RAID" modules to access the array. The difference is that you don't have to get personally involved in actually configuring the array with "mdadm" when you use "dmraid" with a FakeRaid device.

Does that help?
 
Old 03-19-2007, 06:50 PM   #6
Kvetch
Member
 
Registered: Mar 2004
Posts: 35

Original Poster
Rep: Reputation: 15
Yes it does, thanks. I have used the kernel's software raid before and have no issues using mdadm instead of the bios raid so I will probably just use the kernel raid by itself and not use the dmraid.

Thanks,
Nick
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Installing Slackware 10.2 on SATA drive with a SATA CD-RW drive Voltar Slackware - Installation 19 08-01-2007 04:33 PM
using GRUB 1.5 with boot on sata-drive and system on usb drive(ipod photo) Scorp-D Linux - Laptop and Netbook 1 03-16-2007 02:34 AM
Installing Kubuntu on SATA drive fails, KV8-MAX3, Maxtor HD, On-board raid controller darkon06 Linux - Hardware 5 05-01-2006 09:31 PM
Mount SATA drive (not RAID) EcceVery Debian 3 08-31-2004 05:47 PM
Reading from RAID 0 SATA NTFS Drive fizgigtiznalkie Linux - Hardware 5 08-29-2004 03:18 PM


All times are GMT -5. The time now is 09:29 PM.

Main Menu
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration