On Ubuntu, RAID and GRUB
On Ubuntu, RAID and GRUB
I acquired an old yet entertaining HP Proliant Microserver N40L. Everything seems fine so far. It has four drives with different capacities. By default, I can use RAID 0, 1, or 10 (or a mix of the three, including RAID 10 for all drives) and JBOD. A modified BIOS would allow me to set up RAID 5, but that’s still in the future... I have already managed to install Ubuntu 14.04 LTS on my Dell PowerEdge 2900 in RAID 1 without any problems, so I expected similar results here. Unfortunately, that didn’t work out. The GRUB installation fails with a "fatal error." Looking into forums suggests the RAID functionality in the N40L isn’t a genuine hardware RAID controller but rather a software-based fakeRAID (uncertain, though there’s a BIOS setup page reachable via Ctrl-F before the OS loads). It appears GRUB gets mixed up and can’t install properly. I’ve tried several fixes from askubuntu forums and other sources, but either I’m applying them incorrectly or misinterpreting the steps. In short, I’m finding it hard to grasp the instructions. I’m okay with letting GRUB stay on a single partition (which would be safe if any drive fails) and just need clear, step-by-step guidance. The hardware is modest, so I prefer sticking with 14.04LTS, but if a newer version can automatically fix these issues, I’d appreciate your help. Anyone willing to assist?
Start by updating to version 18.04—it's the latest release. Why are you planning to use it in a RAID configuration? Just for testing? In my setup, I typically install an SSD as a standalone drive, run the operating system on that, and then rely on RAID devices for storage. I've used Windows across three SSDs in RAID 0 before, and it performed well. However, that setup was on a server board with a dedicated RAID controller. For your needs, I recommend avoiding RAID altogether and installing the OS directly on a single drive. Regarding your question about using four drives of different sizes, it's generally not ideal with RAID—you'll likely be constrained by the smallest capacity or may need to partition larger drives. As for documentation, I searched online but couldn't locate a user guide for that specific server configuration... RAID guides should be available there.
Maybe it will work, but does it address the problem? Yes, I understand this—I had what I thought I needed. Bigger drives are ordered, though they're not available yet. They should arrive, but they haven't. The standard documentation is for Windows Home Server, which has been discontinued a while back. That means HP isn't very helpful here. I think it's more about software RAID, since Ubuntu 14.04 LTS doesn't have any hardware RAID issues...
Likely won't resolve the issue, but it's always worth trying. You're not leveraging software RAID here, you're relying on a motherboard fake RAID setup. Disable that and switch to software RAID in the operating system (go to btrfs here). The simplest alternative might be installing on one drive with BTRFS, then adding the others and adjusting the RAID level while it's active.
This will likely be a better choice compared to the motherboard fake RAID setup.
Absolutely, that works. Just avoid the fake RAID setup—it's not recommended.
Initially, your setup lacks true hardware redundancy, relying on a motherboard fake RAID that's unreliable and also utilizes the CPU. It's generally poorly constructed and primarily intended to allow Windows booting from it. Software RAID offers several benefits over this approach—flexibility to relocate data across systems without physical hardware, no requirement for additional cards, optional checksums for data integrity, enabling recovery of corrupted files and fixing bit rot (hardware RAID can't verify drive accuracy), enhanced command-line control, and the ability to combine different RAID levels with caching. It provides superior support compared to most hardware RAID solutions. With extra system RAM, caching performance improves significantly on SSDs, though you must store the cache database somewhere. Expansion is simpler, supporting drives on various controllers. Yes, Linux offers robust software RAID options like ZFS and Btrfs, which feature more capabilities than hardware RAID and are widely adopted in professional environments. Since you're not using a dedicated hardware RAID card, it's a much better alternative than the fake RAID solution.