I have an Adaptec RAID-Controller and created an RAID-1(Mirroring) succesfully. Now I have installed Ubuntu Server 12.04.3. When I type fdisk -l I get this output: bf@fileserver:~$ sudo fdisk -l Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00000000 Disk /dev/sda doesn't contain a valid partition table Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00000000 Disk /dev/sdb doesn't contain a valid partition table Disk /dev/sdc: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders, total 156301488 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0004c454 Device Boot Start End Blocks Id System /dev/sdc1 * 2048 499711 248832 83 Linux /dev/sdc2 501758 156301311 77899777 5 Extended /dev/sdc5 501760 156301311 77899776 8e Linux LVM Disk /dev/mapper/fileserver--vg-root: 75.6 GB, 75606523904 bytes 255 heads, 63 sectors/track, 9191 cylinders, total 147668992 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/fileserver--vg-root doesn't contain a valid partition table Disk /dev/mapper/ddf1_Data: 1000.1 GB, 1000065728512 bytes 255 heads, 63 sectors/track, 121584 cylinders, total 1953253376 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00000000 Disk /dev/mapper/ddf1_Data doesn't contain a valid partition table Disk /dev/mapper/fileserver--vg-swap_1: 4160 MB, 4160749568 bytes 255 heads, 63 sectors/track, 505 cylinders, total 8126464 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/fileserver--vg-swap_1 doesn't contain a valid partition table The 80 GB HDD is for the System The 1000.2 GB HDD should be for my data. But I'm a bit confused becauser there are listed two 1000.2 GB HDDs, due the Hardware RAID shoudln't there be only one HDD vissible to the OS? (I have two 1000.2 GB HDDs in an Raid-1 Array) dmraid gives me bf@fileserver:~$ sudo dmraid -r /dev/sdb: ddf1, ".ddf1_disks", GROUP, ok, 1953253376 sectors, data@ 0 /dev/sda: ddf1, ".ddf1_disks", GROUP, ok, 1953253376 sectors, data@ 0 so It seems to be ok? But how do I partitionate this disks and which one should I mount(sdb or sda?) Hope you can help me thx Florian