trying to access software raid0 in ubuntu.

[Rashkae]

Art Baldini wrote:
> I have 2 500 G SATA hard drives that I had in a NAS.  They were set up in a
> RAID0 using the NAS S/W.  It appears to have used Linux to create the RAID0.
> 
> The disks have 3 partitions,
> fdisk -l shows...
> Disk /dev/sdb: 500.1 GB, 500107862016 bytes
> 255 heads, 63 sectors/track, 60801 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x079bacbe
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdb1               1           7       56227   fd  Linux raid
> autodetect
> /dev/sdb2               8       60769   488070765   fd  Linux raid
> autodetect
> /dev/sdb3           60770       60801      257040   82  Linux swap / Solaris
> 
> Disk /dev/sdc: 500.1 GB, 500107862016 bytes
> 255 heads, 63 sectors/track, 60801 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x32af16a3
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1               1           7       56227   fd  Linux raid
> autodetect
> /dev/sdc2               8       60769   488070765   fd  Linux raid
> autodetect
> /dev/sdc3           60770       60801      257040   82  Linux swap / Solaris
> 
> 
> If I put the disks in a CentOS system the md shows up and I can access the
> raid0 device.
> When I put them in my ubuntu (9.10) system is sees the physical disks, and
> the partitions but I cannot access the md.
> The mdstat file shows:
>     cat /proc/mdstat
>     Personalities :
>     unused devices: <none>
> The GUI Disk Utility sees the disks, partitions, and lists that there is a
> RAID device and it lists the sdb2, and sdc2 partitions.  I would prefer to
> not have to back up all the data and rebuild the RAID, and I am fairly new
> to Ubuntu so I dont know all the utilities.  I have seen mention of dmraid
> in some forums, but when I run sudo dmraid -ay I get:"no raid disks"
> 
> thanks.
> Art
> 
> 

Believe it or not, this is done on purpose so that arrays don't start on
systems when hard drives are moved around... don't ask me why.
(Presumably, this has been the cause of other problems)

Try sudo mdadm --assemble --scan --auto-update-homehost

That should at least get the arrays up.  However, I do not know if it
will be sufficient to get the drives working on boot without more work.