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I have a HP Proliant microserver gen 8 on which I am planning on installing Debian. I was thinking of setting up a raid-1 configuration through the built in raid controller using two Western Digital Red 3TB drives, which would give me a total capacity of 3 TB. However, the server has not got support for UEFI which I read here (3.6.3) would only allow for a boot drive of maximum 2TB. I guess this has to do with the fact that the boot drive needs to be MBR on a BIOS system?

So I was thinking, would it be possible to put /boot on a MBR partition of a few GBs, and have the rest of the system on a GPT partition. Would that work on a BIOS system and is it "Good Practice"? Should I instead go for two 2 TB drives?

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  • iirc the raid card would need to support 3tb disks. Another option might be to use a USB drive - I do believe the mini servers have an internal sd card or USB option?
    – Journeyman Geek
    Jul 12, 2015 at 0:35
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    Some clarification is needed here. There is no such thing as an "MBR partition" or a "GPT partition". There are MBR disks, and GPT disks. These terms refer to the type of partition table. The MBR partition table format is the only one that BIOS firmware can use to boot, and it only supports a maximum of 2 TiB-sized disks. The Debian approach with the bios_grub partition is a hack: see askubuntu.com/questions/500359/… and en.wikipedia.org/wiki/BIOS_boot_partition As gravity stated, Windows won't like that one bit. Jul 12, 2015 at 3:58

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Yes, GPT works fine with most BIOSes – as the BIOS boot process really only involves running the bootcode in sector 0, and it's up to that bootcode to actually interpret whatever partition table it needs.

(For example, syslinux has separate MBR & GPT versions of the bootcode, and LILO just hardcodes the offsets instead.)

Similarly, it's up to the operating system to interpret partition tables once it has booted (it doesn't ask the BIOS for that) – your data disks can use MBR, GPT, APM, … as long as the OS supports it.

So yes, creating a small MBR disk for booting would work. It's quite common – often it's whole point of having a separate /boot partition.


Also, if you were to install Windows, having separate OS and data volumes would be the only way, as it really doesn't like mixing BIOS & GPT, nor UEFI & MBR.

Linux works just fine with either approach though. (Though, if splitting into two disks, I'd put the whole / on the MBR one, since allocating several gigabytes to /boot is a huge waste.)

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  • So, if I understood you correctly, I should be fine with one single GPT partition occupying the whole disk? I don't need a MBR partition?
    – Scraph
    Jul 12, 2015 at 1:27
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    See my comment above to your question. Jul 12, 2015 at 3:59
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    "MBR volume" is not correct. The OP can create a GPT disk and boot from there, because Linux supports it
    – phuclv
    Jul 12, 2015 at 4:20
  • I'm good with the first three paragraphs of this answer. There's no need to drag a separate MBR disk into it to hold /boot, though; as you say, modern BIOS-mode boot loaders can handle GPT just fine. A few BIOSes have quirks that need working around, but they're rare. A separate /boot partition located below the 2TiB mark is advisable because some BIOSes have 32-bit sector-value limits.
    – Rod Smith
    Jul 12, 2015 at 23:59
  • @Rod Ah, yes, I probably got stuck thinking about a similar Gen8 install I've done myself – which had Windows instead, which wouldn't have liked GPT there. Jul 13, 2015 at 9:07
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You shouldn't have to - looking at the specs for the microserver, it probably has UEFI (it's a semi-modern core i3 or i5 - and those have never come with bios). It might have an 'old school' text interface for the bios but that's fine.

The system apparently officially supports 4tb drives anyway.

If you wanted to do an exotic boot, and wanted a seperate /boot or more, the microservers have an internal SD card or USB port.

tldr: It'll boot fine on 3tb disks, and boots off UEFI not BIOS.

I used this review and the quickspecs pdf linked on the model page for reference.

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  • AFAIK, most Gen8's do have a BIOS, except DL580 apparently. Jul 12, 2015 at 0:46
  • It actually has a Intel Celeron G1610T.
    – Scraph
    Jul 12, 2015 at 1:02
  • That's my server, 4 tb drives in a raid, then a usb3 flash drive to boot it from Jul 12, 2015 at 2:28
  • Hm. That would be odd, and the microservers essentially use desktop/laptop processors and chipsets anyway. The fact that it officially supports bigger drives means what OP thinks he needs to do shouldn't be necessary
    – Journeyman Geek
    Jul 12, 2015 at 8:59
  • According to this site, the Proliant Gen8 models are BIOS-only, not UEFI-based. (Like grawity, I also found a reference to the DL580 being an exception to this rule.) In any event, as psusi says, Linux boots fine on GPT disks even on most BIOS-based systems. Dual-booting would complicate that, but dual-booting a server is unlikely to make sense. I recommend creating a separate /boot partition below the 2TiB mark, though; this is necessary to work around BIOS limits on some systems.
    – Rod Smith
    Jul 12, 2015 at 23:56
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Debian will install and boot just fine on a GPT partitioned disk in a BIOS booting system. All it requires is a 1 mb bios_grub partition.

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