# Help setting up ICH9 raid5

## thedaemonhunter

Hi All

I am looking to move back to Gentoo as my primary OS, i have a few questions though.

I currently run windows Vista (Please dont start flaming my thread for this.....) and i like the way my drives are setup. I am running on a Gigabyte board with the intel ip35 chipset

and have 2 RAID arrays, 

RAID0 accross 2x250GB (for OS) to be formatted  for Gentoo / /boot and swap

RAID5 accross 5x320GB (forStorage) - to be left untouched at install

I want to install Gentoo on the RAID0 array, and mount the existing RAID5 (NTFS) within Gentoo.

Now as the RAID5 is controlled by intels ICH9 chipset i think Linux will see 5 seperate drives? havn't checked this yet, can i get Gentoo to accept my current RAID5 without risks?

*edit  - Some of you might be wondering why i want NTFS.. i will be moving all the data from the RAID5 onto a 1TB disk i have spare and will format the RAID5 as ext3, then move everything back.... i need to get Gentoo running first tho...

Regards

Thedaemonhunter

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## bunder

raid these days is a pain, mostly due to the fact that newer raid cards are nothing more than an IDE controller with a fake BIOS and a windows driver that does the actual raid.  don't bother with fakeraid/dm_mapper, and install mdadm.  

to answer your question, yes all the drives should show up as single drives... that is unless you in fact do have a real raid chip, albeit unlikely.

cheers

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## thedaemonhunter

So will i be able to build RAID5 with mdadm without trashing the disks? and will mdadm see the current NTFS volume that is on these disks? i am really scared of trying this   :Sad: 

Regards

Thedaemonhunter

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## bunder

 *thedaemonhunter wrote:*   

> So will i be able to build RAID5 with mdadm without trashing the disks? and will mdadm see the current NTFS volume that is on these disks? i am really scared of trying this  
> 
> Regards
> 
> Thedaemonhunter

 

since mdadm uses the raid partition type, i don't think you'd be able to integrate ntfs into md format.  and if you did, i don't think windows would want to look at it afterwards...  if that's not a problem, i still think it would require you copying the data off the drive and then back again with the right partition/fs setup.

cheers

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## thedaemonhunter

 *Quote:*   

> since mdadm uses the raid partition type, i don't think you'd be able to integrate ntfs into md format.

 

Ah yeah that makes sense, ok i need to go through some pain first and get everything off of the RAID5 first.

Thanks for the A1 support

I will post back as i progress

Regards

Thedaemonhunter

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## s4e8

In order to access ata raid5, you need dm-raid45 kernel patch.

This patch is dead though, it wont work with newer kernel.

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## thedaemonhunter

 *Quote:*   

> In order to access ata raid5, you need dm-raid45 kernel patch. 
> 
> This patch is dead though, it wont work with newer kernel.

 

You gotta be kidding!

So i cant build a RAID5 array??

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## drescherjm

Just not one that you can share with windows. At one time I was waiting for an updated patch but I gave up. And after I measured the horrible performance with software raid under windows I removed the raid from windows and went with individual disks. Apparently windows does not have a stripe cache so that every write if it is smaller than the chunk size the entire stripe will always be read before it is written even if the next write is in the chunk at least this is what happens on nVraid and so it makes raid 5, 6 and 10 slower than a single disk instead of faster for large operations.

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## thedaemonhunter

Hmmm well i got all my data off of the RAID5 i will start the install tonight the easiest way to find out what i can/cant do is to try

Regards

Thedaemonhunter

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## thedaemonhunter

Hi again....

Firstly 

 *Quote:*   

> In order to access ata raid5, you need dm-raid45 kernel patch.
> 
> This patch is dead though, it wont work with newer kernel.

 

This is not true, i have created a RAID5 array with no issues

i now have

2x250gb disks

128mb /boot  -RAID1

4gig swap      -RAID0

495gig /         -RAID0

5x320gb disks

1.2tb /storage  -RAID5

Everything was straight forward, compiling kernel as i type this  :Smile: 

ThedaemonhunterLast edited by thedaemonhunter on Thu Sep 04, 2008 3:36 pm; edited 1 time in total

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## drescherjm

 *Quote:*   

> This is not true, i have created a RAID5 array with no issues 

 

You did this with mdadm right?

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## thedaemonhunter

yup 

```
mdadm --create --verbose /dev/md4 --level=5 --raid-devices=5 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1
```

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## drescherjm

Then what the other user was getting at with the dm-raid45 is you can not use this raid array under windows. The only way to share a raid5 or 6 array with windows and linux is with dm-raid45 or a hardware raid controller.

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## thedaemonhunter

OIC what you mean, yeah that makes sense  :Smile: 

I thought it seemed strange.....  my bad

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