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I am installing Debian 6 on a server, a HP Proliant DL380 G4. It comes with 6 hard disks. Originally it had Windows server and I could see only see 3 hard disks (the other three said the Admin, were used as RAID 1) , so, now I want to install Debian and curiously when I want to format the disks I cant see the 6, just 3... why is this? do I have to do something special for make it recognize them?

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The 6 physical disks form 3 logical disks. What operation would you want to perform on a physical disk that makes any sense while it's part of a logical disk? – David Schwartz Jan 28 '13 at 5:11
up vote 3 down vote accepted

The disks (and RAID arrays) are being managed by the hardware RAID controller in your server. My guess is that the six drives are currently configured as three RAID1 pairs, which is what your OS is seeing. If you truly want to expose all six hard drives to the OS, you will need to go into the RAID controller BIOS and re-configure things.

I would highly recommend, though, letting the hardware RAID controller handle RAID for you. No offense, but judging from your level of familiarity with storage, the hardware RAID controller will likely do a much better job managing things than you will with software RAID.

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thanks!! so, I should install only the OS and let the on board raid software to handle all?? in this case means I would only let one partition for swap, other for root and the other disks only formated for the use at the future??? – user156355 Jan 28 '13 at 5:14
Yes, use the on-board RAID card, not software RAID. For simplicity's sake, I'd recommend putting 5 drives into a RAID6 array, leaving one as a hot spare. Then you can partition that logical volume however you see fit for your application. – EEAA Jan 28 '13 at 5:16
@user156355 I would use the six disks in a RAID 1+0. But the configuration for that server's RAID controller needs to be done in the BIOS, as I point out in my answer. You will have to delete the existing RAID configuration in order to use the disks the way you want. – ewwhite Jan 28 '13 at 5:28
@ewwhite Good point - thanks for the clarification. – EEAA Jan 28 '13 at 5:31
thanks all you, I didnt change any on the BIOS, so, still default RAID, right? the server its a little old but also big for my application, so, I think with the default RAID is enough. Thanks – user156355 Jan 28 '13 at 6:40

This is an older HP ProLiant DL380 G4, so it has either the onboard Smart Array 6i controller or an add-in Smart Array 641 or Smart Array 6400-series RAID controller installed.

In all cases, the RAID controller can be configured during the system's POST process. A simple RAID configuration can be performed by pressing F8 when prompted when you see the HP Option Rom Configuration for Arrays BIOS utility (video link).

If you intend to reformat this system and install Debian, and you're okay with deleting the old data on the server, you'll want to create a new "Logical Drive" in the BIOS utility.

A typical setup would be all six disks in a single RAID 1+0 or RAID 5 configuration. Follow the on-screen prompts to do this.

The result of a configured logical drive is that the RAID controller will present one logical disk to the operating system. You can carve this into the partitions you need for Linux. In this basic setup, you should not see 2, 3 or 6 disks at the OS level, but rather one target that's a logical representation of the raided disks. The chances are that the device will present itself as dev/cciss/c0d0 or simply /dev/sda.

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