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I've read that running multiple operating systems/boot partitions in RAID arrays doesn't always work as planned and is difficult at best. Is this true only of software RAID arrays? If so, that makes a lot of sense, as software RAID would run at the operating system level and if you have multiple operating systems, each one would have to be configured with RAID to work. Is it any easier to, for example, have a dual-boot system (Linux/Windows) in a hardware-driven RAID-10 array?

Will I be able, for instance, to install Linux (swap partition, ext4 partition for /, another ext4 partition for /home) alongside a Windows install (one NTFS partition) on a hardware RAID setup running two SSDs in RAID-0?

Naftuli Kay
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  • I would say Yes because the bloodloader would load very early. My guess is with software RAID the OS would load before any bootloader so any initalising of partitions (due to the OS selected) would have to be ordered then processed with a reboot/reset. – HaydnWVN Jan 09 '12 at 12:56
  • That's what you'd think, right? The BIOS should really only see one 'drive' for my array, correct? I've never done hardware RAID before, so I'm not sure what setup looks like. – Naftuli Kay Jan 09 '12 at 13:11
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    Most hardware RAID is configured by a different firmware (ie not in the BIOS, but comes just after POST). Some BIOS' with an inbuilt RAID will show the array name, whatever it may be... Some don't... Some have the Controller/Array name as a boot device... – HaydnWVN Jan 09 '12 at 14:05

2 Answers2

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If the hardware RAID is capable of handling INT 13h then it will support any OS you can throw at it, from the earliest versions of DOS all the way to Windows 8/Linux 3/FreeBSD 9 and beyond. The OS will have to support the hardware RAID to get anywhere after the bootloader, of course.

Ignacio Vazquez-Abrams
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  • Why does the OS have to be aware that it's running in hardware RAID? Isn't the whole point of hardware RAID to obscure drives behind the controller and present essentially one drive per array to the OS, so that the OS utilization of hardware RAID is completely transparent? – Naftuli Kay Feb 01 '12 at 06:04
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    It's doesn't need to care that it's running on hardware RAID. It *does* however need to be able to use the API provided by the controller in order to read and write data. – Ignacio Vazquez-Abrams Feb 01 '12 at 06:16
  • Int 13h does not pertain to modern systems which use [UEFI](http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface) rather than BIOS. – harrymc Feb 01 '12 at 06:55
  • @harrymc, I can't think of any current PC OS which requires UEFI (and cannot use BIOS) for bootstrapping. And IIRC, UEFI specifically provides a BIOS compatibility layer. – user Feb 01 '12 at 10:30
  • @Michael Kjörling: When booting with UEFI, a UEFI-aware OS will not use int 13h. This answer doesn't apply to the question. – harrymc Feb 01 '12 at 11:35
  • Does that mean that if I found a way to install OSX on said computer with RAID array, it wouldn't be able to boot? – Naftuli Kay Feb 01 '12 at 15:42
  • If you managed to install, that means you already booted from the dvd, and that normally means that you will be able to boot the installed OS. However, problems may arise if you try to install two OSs, one using BIOS and the other UEFI, or even a mixture of UEFI versions 1 and 2. See for example my answer to [this question](http://superuser.com/questions/382442/mac-pro-wont-boot-from-windows-7-dvd-flashing-prohibitory-sign). – harrymc Feb 01 '12 at 16:21
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(This answer is oriented for Linux. But this is probably very similar for Windows.)

I believe that the answer is Yes - you can use Linux to partition a RAID.

See the article Linux Hardware RAID Howto for advice as regarding partitioning the RAID and configuring the kernel.

The article Installing Ubuntu Server on hardware RAID is interesting to read. It details the experience of one person when installing Ubuntu on a RAID and underlines the importance of having the right drivers. The article actually includes a workaround for the case where the RAID driver is missing, so Linux can see the disks but not the RAID. The simple solution is to install on one of the disks (swapping the other out) and only afterward building the RAID.

harrymc
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