can I mount my WinXP software RAID 0 array in Ubuntu/Kubuntu?

[BobTheDinosaur9]

*posted here cos i figured the server guys would know a thing or two about raid...

The title pretty much says it all, i've got 4 500's in 2x RAID 0 arrays, i.e. two RAID disks

in ubuntu/kubuntu i can see them as unidentified volumes, thing is, i don't know how to mount them and when i just right click and choose mount it complains about RAID/LDM

please take into account that i'm a complete noob, i installed and viewed linux for the first time in my whole life 2 days ago

thanks in advance

p.s. i have managed to install my dell laptop wifi drivers using terminal, i didn't know what i was doing though...

[beniwtv]

Hi,
How did you create the raid? What program did you use?

Cheers,

[BobTheDinosaur9]

window's built-in disk management software utility, i created dynamic disks and then raid 0'ed them

[beniwtv]

I think it's not possible then. Windows and Ubuntu use their own specifications for creating raid. AFAIK, they're not compatible (someone correct me if I'm wrong, though).

Cheers,

[Martigen]

I think it's not possible then. Windows and Ubuntu use their own specifications for creating raid. AFAIK, they're not compatible (someone correct me if I'm wrong, though).

Cheers,

Piffle, this is Linux, anything is possible

Bob -- yes you can, I do it myself. But as a less-than-common scenario there's no user-friendly tool to make it easy.

The Linux kernel includes the 'md' (multiple disk) driver to manage Linux software RAID devices. What isn't common knowledge is that Windows software RAID uses an identical structure, bar superblocks (don't worry about these for now). So, Linux being awesome as it is, can in fact mount Windows software RAID devices -- as long as you tell it where they are (and that's where superblocks come in for Linux, enabling auto-building arrays).

Here'a a quick how-to:

1. First make sure you've got the 'mdadm' tools installed:

sudo apt-get install mdadm

2. Now determine the partitions being used for your Windows array. If you know these already, great, if not check your partitions like so:

cat /proc/partitions

On my system, for example, I get:

major minor  #blocks  name

[...output cut...]

   8    32  146523384 sdc
   8    33   10485760 sdc1
   8    34   10483712 sdc2
   8    35  125548544 sdc3
   8    48  146523384 sdd
   8    49   10485760 sdd1
   8    50   10483712 sdd2
   8    51  125548544 sdd3

For me, my Windows RAID array is built from /dev/sdc2 and /dev/sdd2 (my sdc1 and sdd1 are my Linux RAID boot)

3. Start the array with mdadm, create a directory to mount it, and then mount it:

sudo mdadm --build /dev/md0 --chunk=64 --level=0 --raid-devices=2 /dev/sdd2 /dev/sdc2
sudo mkdir /media/Windows
sudo mount -t ntfs /dev/md0 /media/Windows

And that's it! The new 'Windows' mount will appear on your desktop to access.

Helpful stuff to know

* Make sure Windows was shutdown cleanly before booting Linux. If not, both the array and mounting with NTFS will likely refuse to work.
* If an array still won't build (an error is reported), try swapping the devices around -- for eg '/dev/sdc2 /dev/sdd2' instead of '/dev/sdd2 /dev/sdc2'. The order they are used to build the array is important.
* Windows software RAID actually uses a chunk size of 128k, but the Linux md driver wants to know the chunk size per device in the array, and so we use 64. You can actually build it with 128 too, but if you mount it you'll see missing files and directories (and whatever you do, do not write to it in this mode!)
* The 'mdadm' command comes with an --assemble option, but this is for super-block (Linux based) arrays. Hence we use --build which will assemble arrays regardless of superblocks and on the assumption the user knows what they are doing (and, in this case, allows us to mount Windows arrays).
* Run 'cat /proc/mdstat' to see the active arrays on your system.

Finally you said you have two RAID 0 arrays -- don't forget to increment '/dev/md0' to '/dev/md1' for your second array, and create another directory to mount it on, so you can access both arrays from your desktop.

[beniwtv]

Piffle, this is Linux, anything is possible

Ha! I stand corrected then. And yes, in Linux everything seems possible.

[BobTheDinosaur9]

Piffle, this is Linux, anything is possible

Bob -- yes you can, I do it myself. But as a less-than-common scenario there's no user-friendly tool to make it easy.

The Linux kernel includes the 'md' (multiple disk) driver to manage Linux software RAID devices. What isn't common knowledge is that Windows software RAID uses an identical structure, bar superblocks (don't worry about these for now). So, Linux being awesome as it is, can in fact mount Windows software RAID devices -- as long as you tell it where they are (and that's where superblocks come in for Linux, enabling auto-building arrays).

Here'a a quick how-to:

1. First make sure you've got the 'mdadm' tools installed:

sudo apt-get install mdadm

2. Now determine the partitions being used for your Windows array. If you know these already, great, if not check your partitions like so:

cat /proc/partitions

On my system, for example, I get:

major minor  #blocks  name

[...output cut...]

   8    32  146523384 sdc
   8    33   10485760 sdc1
   8    34   10483712 sdc2
   8    35  125548544 sdc3
   8    48  146523384 sdd
   8    49   10485760 sdd1
   8    50   10483712 sdd2
   8    51  125548544 sdd3

For me, my Windows RAID array is built from /dev/sdc2 and /dev/sdd2 (my sdc1 and sdd1 are my Linux RAID boot)

3. Start the array with mdadm, create a directory to mount it, and then mount it:

sudo mdadm --build /dev/md0 --chunk=64 --level=0 --raid-devices=2 /dev/sdd2 /dev/sdc2
sudo mkdir /media/Windows
sudo mount -t ntfs /dev/md0 /media/Windows

And that's it! The new 'Windows' mount will appear on your desktop to access.

Helpful stuff to know

* Make sure Windows was shutdown cleanly before booting Linux. If not, both the array and mounting with NTFS will likely refuse to work.
* If an array still won't build (an error is reported), try swapping the devices around -- for eg '/dev/sdc2 /dev/sdd2' instead of '/dev/sdd2 /dev/sdc2'. The order they are used to build the array is important.
* Windows software RAID actually uses a chunk size of 128k, but the Linux md driver wants to know the chunk size per device in the array, and so we use 64. You can actually build it with 128 too, but if you mount it you'll see missing files and directories (and whatever you do, do not write to it in this mode!)
* The 'mdadm' command comes with an --assemble option, but this is for super-block (Linux based) arrays. Hence we use --build which will assemble arrays regardless of superblocks and on the assumption the user knows what they are doing (and, in this case, allows us to mount Windows arrays).
* Run 'cat /proc/mdstat' to see the active arrays on your system.

Finally you said you have two RAID 0 arrays -- don't forget to increment '/dev/md0' to '/dev/md1' for your second array, and create another directory to mount it on, so you can access both arrays from your desktop.

wow! thanks man, i must say linux is quite impressive, i'm an utter noob though, only acquired it about 3 days ago, so a lot of what your saying is greek to me, i've read a bit on how linux defines disks but that last bit about incrementing for my second array, could you help me understand that a little bit better?

[jakub12]

I am joining in this thread since I am attempting to do the same thing, access my Raid 0 where my Windows is installed.
I followed the suggested procedure: here is what I got:

jakub@jakub-desktop:~$ cat /proc/partitions
major minor #blocks name

8 0 156290904 sda
8 1 30716248 sda1
8 2 30716280 sda2
8 3 1 sda3
8 4 47664480 sda4
8 5 1951866 sda5
8 6 1951866 sda6
8 7 9767488 sda7
8 8 3903763 sda8
8 9 5855661 sda9
8 10 979933 sda10
8 11 1951866 sda11
8 12 1951866 sda12
8 13 16603146 sda13
8 14 2273166 sda14
8 16 244198584 sdb
8 17 244196001 sdb1
8 32 244198584 sdc
8 33 122881153 sdc1
8 34 1 sdc2
8 48 244198584 sdd
253 0 488397056 dm-0
253 1 122881153 dm-1
jakub@jakub-desktop:~$ sudo mdadm --build /dev/md0 --chunk=64 --level=0 --raid-devices=2 /dev/sdb1 /dev/sdc1
[sudo] password for jakub:
mdadm: Cannot open /dev/sdc1: Device or resource busy
jakub@jakub-desktop:~$ sudo mdadm --build /dev/md0 --chunk=64 --level=0 --raid-devices=2 /dev/sdc1 /dev/sdb1
mdadm: Cannot open /dev/sdc1: Device or resource busy
jakub@jakub-desktop:~$

My Windows is on /dev/sdb1 and /dev/sdc1 array.It seems that there is something weird with my sdc2 partition- it's not supposed to be there, don't know where it came from. Is it possible that "Device busy" message is caused by that?

Thanks,
Jakub

[jakub12]

I have solved my problem as per solution in this thread: http://ubuntuforums.org/showthread.php?t=184934.

The code:
sudo dmraid -r
/dev/sdd: nvidia, "nvidia_ibfbejec", stripe, ok, 488397166 sectors, data@ 0
/dev/sdc: nvidia, "nvidia_ibfbejec", stripe, ok, 488397166 sectors, data@ 0

sudo dmraid -ay
RAID set "nvidia_ibfbejec" already active
RAID set "nvidia_ibfbejec1" already active

sudo mkdir /media/raid "should have named it something more imaginative

sudo mount -t ntfs /dev/mapper/nvidia_ibfbejec1 /media/raid

After that an icon named "raid" on my desktop appeared as if by magic.

Thanks a million guys for all your suggestions,
Jakub

[Martigen]

wow! thanks man, i must say linux is quite impressive, i'm an utter noob though, only acquired it about 3 days ago, so a lot of what your saying is greek to me, i've read a bit on how linux defines disks but that last bit about incrementing for my second array, could you help me understand that a little bit better?

Sure -- I'll break down the command and show you what it's doing:

sudo mdadm --build /dev/md0 --chunk=64 --level=0 --raid-devices=2 /dev/sdd2 /dev/sdc2

As you probably know commands take 'switches' and we have a number here:

--build        : Tells mdadm to build a new array
/dev/md0       : Is the RAID array under Linux we want to create
--chunk        : Specifies the chunk size to use (see my previous post)
--level        : The RAID level, of course, which is 0 for RAID 0
--raid devices : Number of drives or partitions in the array we are building
/dev/sd...     : The drives or partitions making up the array

On drives under Linux -- all devices exist under the /dev directory, and for drives specifically you'll find they all start with 'sd' for 'scsi disk'. SATA drives come under scsi for the purposes of the kernel. Pulling apart an example device:

/dev/sda1
      ^^^-- Partition number on drive
      ||--- Drive number on controller
      |---- Device type (scsi drive)

So for example /dev/sda1 is the first partition on the first drive, /dev/sdc4 would be the fourth partition on the third drive, and so on.

Now to your question about incrementing 'md'. Remember the 'md' driver builds RAID arrays under Linux so, just like a hard drive, an array appears to Linux as just another device. And since you can have many arrays, each one is numbered just like drives and partitions are. So for example /dev/md0 is the first array, /dev/md1 the second and so on.

So if you want to mount both your arrays, you will be creating two arrays with the 'md' driver using the mdadm command, and you'll want to specify a new md device to create for each, like so (note your specific partitions to build the arrays from are probably different, this is just an example):

sudo mdadm --build /dev/md0 --chunk=64 --level=0 --raid-devices=2 /dev/sdd2 /dev/sdc2
sudo mdadm --build /dev/md1 --chunk=64 --level=0 --raid-devices=2 /dev/sdd3 /dev/sdc3

Would create a RAID array /dev/md0 from partitions /dev/sdd2 and /dev/sdc2 and a RAID array /dev/md1 from partitions /dev/sdd3 and /dev/sdc3.

Hope that helps!

I have solved my problem as per solution in this thread: http://ubuntuforums.org/showthread.php?t=184934.

The code:
sudo dmraid -r
/dev/sdd: nvidia, "nvidia_ibfbejec", stripe, ok, 488397166 sectors, data@ 0
/dev/sdc: nvidia, "nvidia_ibfbejec", stripe, ok, 488397166 sectors, data@ 0

sudo mkdir /media/raid "should have named it something more imaginative

sudo mount -t ntfs /dev/mapper/nvidia_ibfbejec1 /media/raid

It's VERY important to differentiate Windows software RAID arrays and fakeraid arrays. For everyone reading:

* If you make an array in Windows using Windows' drive management tools -- aka converting one or more disks to 'dynamic' disks and RAIDing two or more partitons --> you have a Windows softraid array, and you need to follow the instructions in the fifth post of the this thread to mount them.

* If you use motherboard based onboard RAID controllers, like Nvidia/Intel etc --> this is what's known as 'fakeraid' -- these controllers provide a hardware interface to an array, and present this to Windows and Linux as a pre-made device. They are called fakeraid because, despite being a 'hardware' solution, all processing is actually still done in software. In any event, RAID arrays made using onboard contollers need to be mounted with the 'dmraid' package, which jackub has covered above.

In summary -- there are two types of RAID array created from Windows, and just as they are accessed in two different ways under Windows, there are two different methods to use these arrays under Linux.