Software RAID 0 HOW-TO

Naughtyus · Posted: Thu Sep 16, 2004 7:15 am Post subject:

I'm having problems with my linear raid setup that perhaps someone here might be able to help me with.

My raidtab is as follows:

tmadhavan · n00b Joined: 26 Aug 2003 Posts: 59 Location: South Wales

I've just set up a RAID-0 on my two 40GB Maxtors (btw, performance increase from 40MB/sec to 65MB/sec - shouldn't it be nearer 80???).

I compiled my kernel with genkernel, so had to add

stig · Posted: Thu Dec 09, 2004 6:39 pm Post subject:

Thanks for the how-to. I've never done this before, and I got raid0 up running in five minutes.
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TrainedChimp · Posted: Wed Dec 29, 2004 5:20 pm Post subject:

Thanks for the HowTo. All went very well for me except that I had to manually create the md* devices, maybe that's becaue I'm running "pure" udev...

Before:

jkcunningham · Posted: Thu Dec 30, 2004 12:19 am Post subject:

How do you manually create the /dev/md* devices? I'm having the same problem.

-Jeff

TrainedChimp · Posted: Thu Dec 30, 2004 12:29 am Post subject:

jkcunningham · Posted: Thu Dec 30, 2004 1:25 am Post subject:

Hey, thanks for the fast reply. Got it. And I discovered that you can get the "scary messages" to go away entirely if you put the persistent-superblock line before the chunksize line. Apparently, when the man page says:

stig · Posted: Thu Jan 06, 2005 12:23 pm Post subject:

I tested the speed of my new md0-device the other day, and the performance results was a little different than I would expect:
I run two seagate barracuda 60 GB disks:

jkcunningham · Posted: Fri Jan 07, 2005 4:39 pm Post subject:

That is curious.

How do you have these hooked up to your mother board? Are they both on the same IDE controller? If on separate controllers, are they both masters or slaves (or one each)? Are these SATA drives?

stig · Posted: Fri Jan 07, 2005 5:17 pm Post subject:

They're master and slave on the same IDE-controller.

jkcunningham · Posted: Sat Jan 08, 2005 1:54 am Post subject:

Hmmm. If they are both on the same cable, then it is by definition a serial event with respect to the two drives (i.e. one gets to write a byte, then the other, etc.). You should try putting them on two different controllers. All modern motherboards have two controllers. Switch stuff around so they are separated and I'll bet you see a big improvement.

-Jeff

stig · Posted: Tue Jan 18, 2005 3:51 pm Post subject:

Hm. Now ALL disks are on separate cables, but the result is still terrible:

jkcunningham · Posted: Tue Jan 18, 2005 4:50 pm Post subject:

I don't know what to make of that. You are running raid-0, right?

stig · Posted: Tue Jan 18, 2005 8:26 pm Post subject:

Indeed I am

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Hoshimaru · Posted: Mon Jan 24, 2005 1:51 pm Post subject:

My motherboard is screwed... Is there a way I can access my md raid 0 with the livecd ? I need to get some data stored on these disks.

I guess booting the system with the old kernel for my former motherboard is a no go :S

I'm so screwed now

augury · l33t Joined: 22 May 2004 Posts: 722 Location: philadelphia

i have a software raid0 i setup on a fasttrack that is now running on an ich5. i didnt use the fasttrack formatter thing in the bios, so my boot partition is ext2 on only one of the disks.
in order for your kernel to mount these software raids, you need to add
md=0,/dev/sda2,/dev/sdb2 root=/dev/md0
and it will read the raidtab and gentoo will mount drives that are not the root although you might be able to pass those to the kernel too.

the bios has the option to load up raid w/ or w/out a bootPROM? ive never heard of this before. im wondering if there would be more speed/less cpu with bootPROM. if i try to boot this way it doesn't boot grub. i could boot the system off of another disk but i dont know if this will work or not.
sda and sdb are 2 80gb barracuda's with the new command caching but my mb doest support it and 16k chunks. Timing buffer-cache reads are 2000 for raid or a boot partion. Timing buffered disk reads ~50-70 on the boot part and 100-113 on the raids. kernel cpu times are very high on one prossesor during tests.

jackxh · n00b Joined: 15 Jan 2005 Posts: 9 Location: LA

Hi Everyone:

First thing. It is an exerecllent how-to.

I followed it to setup the raid1 on this. Everything works. I use kernel 2.6.9.
/ reiserfs. AMD 2000, 512 RAM. Gigabyte MB.

the system boots up. But it is very very slow. Like even when I type return key. It takes .5 sec to respond.

when I do top, I see 80 to 95 CPU use by raid related executeables.

Can anyone please give me a hiting. If I need to configure anything.

Jack

Hoshimaru · Posted: Sun Feb 06, 2005 12:05 pm Post subject:

Appearantly I could boot the system with the new motherboard. I made a backup to another computer and I'm going to install it from scratch again... if I'm able to see the hard disks attached to a HPT372 RAID controller at least :roll:

Phk · Posted: Fri Mar 04, 2005 9:30 am Post subject:

Hi there!

I'm getting mad on trying to put raid 0 working.... :cry:

I'm able to make /dev/md0,
i'm able to do fdisk /dev/md0 and create partitions,
but......
How can i format now a single partition? if my raid (/dev/md0) had two partitions, how could i access each individually?

Please clear my mind or i'll reject technology from now on...

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Hoshimaru · Posted: Fri Mar 04, 2005 11:30 am Post subject:

Why on earth would you want to format individual partition from your /dev/md0 ?
Just format the md0...

fdisking it ? For what purpose ? Once you fdisked 2 or more hard disk and build your mdraid device on a specific partition of all the drives it should be ok.

If you absolutely have to, just mk2fs /dev/hdX or sdX for example.

Phk · Posted: Fri Mar 04, 2005 6:23 pm Post subject:

Ok! So /dev/md0 is the first partition, not the raid itself.......

So my question is:
if i need to partition each drive individually, i don't need the raid mode set in the motherboard, right? If so, how can i have raid working on linux+windows?

I'm gettin confused...
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Hoshimaru · Posted: Fri Mar 04, 2005 11:06 pm Post subject:

Depends on the raid you want.
If you are going to use hardware raid, you need to create the array in your controller's bios and load the correct LKM. The access the raided devices with /dev/ataraid/dXpX, or /dev/sda or other namings... depends on the module. Then it's just partitioning and formatting as if you were using a regular hard disk.

If you want to use linux software raid or (mdraid/mdadm) you might want to check this out: https://forums.gentoo.org/viewtopic-p-2053078.html#2053078

It's for using with a HPT372, but that more or less the same for the rest.

zpet731 · Posted: Wed Mar 30, 2005 3:07 pm Post subject:

Hi everyone,

Just wanted to know if these instructions are still current and are they the same for SATA RAID 0. Also I would like to mention that I just put a system together with GA-K8NF-9 and have two 160GB seagate HD. Now when I boot the bios asks me to setup the raid array. So if Im only using linux I should use software raid right? Does this mean that I should disable the raid for my to SATA drives within the bios.

Thanks!!
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Nikola Tesla

Phk · Posted: Wed Mar 30, 2005 3:52 pm Post subject:

Hi there.

I've managed to build a similar system up, but i've spent 2 weeks making a huge pile of sh*t.
So, i encourage you to follow this:
https://forums.gentoo.org/viewtopic-p-2220169-highlight-.html#2220169
Instead of spending 2 weeks like i did.

(you will basicly only need the gen2dmraid-0.99a.iso. Instructions at the link i gave)
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"# cat /dev/urandom >> /tmp/life"

zpet731 · Posted: Wed Mar 30, 2005 4:51 pm Post subject:

Hey Phk,

If the above note was inteded to me, then I need to ask you should I be using the RAID within the motherboard or just stick to software raid. Im running ONLY linux.
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" Invention is the most important product of man's creative brain. The ultimate purpose is the complete mastery of mind over the material world, the harnessing of human nature to human needs."
Nikola Tesla