# Current state of dmraid

## xanium4332

Hi, I'm wondering what the current state of dmraid is with the current kernel version. There seems to be quite a lot of information about at the moment, but I can'ty seem to find any definite instructions for setting it up.

So, is it easy to setup dmraid with a 2.6.18 kernel at the moment?

Thanks in advance... Xanium

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## NeddySeagoon

xanium4332,

On the basis of not seeing any problems reported here since the kernel/dmraid versioning issues around 2.6.16, I expect it JustWorks.

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## 96140

Well, I've seen far more problems with dmraid over the last few months than I've ever seen with mdadm. dmraid development has been really neglected, in my opinion. That being said, mdadm has always been a superior RAID management tool, so unless you need dmraid to work with fake RAID (aka BIOS raid, like the built-in nVidia RAID that actually needs Windows drivers), I suggest you go with mdadm.

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## xanium4332

Yeah, unfortunately I need to be able to dual boot Windows XP (for games, otherwise I would banish it forever), and I also want to keep my 4 disk RAID0 array (as I want the performance for gaming). The current ebuild for dmraid is hardmasked, generally I take this as a bad sign, so does anyone know why.

Seeing as I am forced to use dmraid (unless anybody has any other ideas, however I need the performance of 4 HDDs in XP (so I can't split them up), and I'd prefer to have the same performance in Gentoo too), does anybody recommend a course of action for the setup of dmraid on a 2.6.18 kernel.

One last thought was to by a hardware Sata-II RAID controller, could be expensive though. Does anybody know if this card is hardware based, as I can buy it for £93.94 incl. VAT). I think it is by looking at the price, however I can't find a specific mention of it being hardware RAID.

Thanks so far, Xanium

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## mbar

 *xanium4332 wrote:*   

> The current ebuild for dmraid is hardmasked, generally I take this as a bad sign, so does anyone know why.

 

I have it working with no problems on Nforce4 mb with fake raid 0 (2 x 250). But I have Gentoo installed on a separate single disk (SATA also), as this is much simpler to setup. I use raid mostly for windows & games, and I have access to all data on my raid within Gentoo.

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## xanium4332

Yeah that's what I originally did (and I didn't need to access my windows partitions at all). What version of dmraid are you using, and how did you set your current situation up.

Just been given a glimpse of hope...

Xanium

UPDATE: Seems that card isn't hardware raid based as it isn't expensive enough...

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## mbar

I just unmasked newest dmraid, enabled relevant device mapper options in kernel, then I did "dmraid -ay" or "dmsetup -ay" (can't remember, I think it was the first command), it mapped nvidia raid partitions to /dev/mapper/.... then I used "dmsetup -table >> /etc/dmraid" to automatically map fake raid to said /dev/...... on reboot. Last thing is to edit /ets/fstab and add relevand mount points/options.

You have to check manuals/help for dmraid and dmsetup (but you don't need to setup raid by hand, use -ay autodetection).

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## xanium4332

so do you think I should just follow the instructions at http://gentoo-wiki.com/HOWTO_Install_Gentoo_with_NVRAID_using_dmraid, and just forget all about the previous problems with dmraid.

I really like Gentoo (and its running on my laptop), but every time I try and switch I end up with either a graphics problem (which have no been fixed thanks to the open source R300 ATI drivers), a kernel problem (2.6.15 was a bad release for my hardware), or a dmraid problem (the current). However I'm not going to loose faith, and most of these problems are caused by Windows and it's majority of the world.

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## xanium4332

OK it seems dmraid is easier to implement now than I originally thought.

All I had to do is:

1. unmask dmraid

2. emerge dmraid

3. emerge genkernel (if not already installed)

4. edit /etc/genkernel.conf, find the section on dmraid, and replace the version number with the installed version of dmraid

5. build initrd with dmraid support (genkernel --dmraid all)

Mileage may vary, as I dont know whether building dmraid with the 'static' use flag 'helped' it work or not.

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