BIOS RAID Settings

I don’t believe you’ll see any difference. From what I can tell, they’re essentially the same, except that setting “RAID mode” allows you to do more with the SATA controller in the future, should you decide to leverage its ability to construct OS-agnostic arrays. (But why would you? You’re only interested in providing direct access for ZFS. Who cares that the BIOS’s “RAID mode” allows you to do more, on top of what AHCI already provides?)

I don’t see where setting the SATA controller to “RAID mode” somehow makes it more direct for ZFS than what “AHCI” already provides.

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I did. It was already explained to you why you should not use RAID mode with your drives. At this point we are beyond TrueNAS related content, hence my suggestion.

As I already explained I am not at all suggesting to use raid.

I tend to agree. I do still wonder why MB manufacturers prefer what is essentially IDE mode though. There are a bunch of other things not supported in IDE mode as well. I’m just intending now to casually keep looking when the topic interests me, and I would report back if I do find anything interesting, however I get the feeling this thread is going to get a barrage of people not reading the thread properly and telling me not to run hardware raid under zfs lol. Maybe they’ll read this last comment and not do that though. :smiley:

Thanks for your concern, however it seems clear you either haven’t read the thread properly or are not understanding it or I am not communication properly. I am not suggesting to run RAID underneath ZFS. I don’t think I should need to point out the specific posts for you. Also, I am running TrueNAS and this is about truenas, though I can see why you might think it isn’t if you assume this is me suggesting running zfs on top of another raid.

How recently? The legacy mode is phased out of newer motherboards, from what I can tell. New boards won’t even have an “IDE mode” option for the SATA controller anymore. Older boards sometimes had three choices for mode: IDE, AHCI, and RAID

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Yeah, this was based on one article I read that listed a few missing commands running raid mode, those of which others have mentioned, specifically NCQ and hot swap. The article inferred that RAID mode therefore was essentially the same as IDE mode. However I have no idea if any other features are enabled or disabled. I’m trying to find a white paper on it, but no luck so far. Chat GPT says some interesting things, but I don’t entirely trust Chat GPT as it’s information comes a lot from popular opinion.

Bro. You shouldn’t run ZFS on top of a hardware RAID. WHY ARE YOU TRYING TO RUN ZFS ON TOP OF A HARDWARE RAID?

Someone stop this man!

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As I’ve said multiple times, I’m not trying to do that.

I think the problem here is that no one really knows if RAID mode vs AHCI mode on your motherboard will make any difference. AHCI mode is pretty well understood and should be fully compatible with ZFS. RAID mode on your motherboard may very well make a few tweaks that could benefit how ZFS works but it could also do some things that interfere with ZFS.

If you want to test how RAID mode behaves and document it for the community, that would be fantastic, just be aware that you’re braving new ground and should make sure your data is backed up.

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It was already explained to you the reason RAID mode is not suitable to run ZFS compared to AHCI mode, thus you continuing to dig the board RAID mode does not seem to me related to TN or ZFS in any way.

So yeah, I and apparently others are having a hard time understanding why you affirm the contrary.

The “RAID” mode enables the small bits of firmware needed for the OS Rapid Storage Technology (RST) software RAID driver to work. It should be little different from AHCI, ideally. In fact, you do not strictly need to have RAID mode enabled to use RST (i.e. fake) RAID, as long as you don’t want to boot from an RST volume.

Ultimately, RST is a joke, even more so than hardware RAID. It’s just crappy software RAID, minimal firmware bits to pretend that there’s something fancy going on, and a trenchcoat to hide this farce.

Enabling RAID mode confers zero advantages (to the extent that booting from RST could be considered an advantage in the first place…) for non-Windows environments. Period.

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I disagree, what has been explained, is not brought with evidence, it is the same opinions that I already have, which are not brought with any facts or references. In a moment, I will post what I have found via Chat GPT, which may or may not be 100% accurate, but I think I have found the bits that answer most of my questions and ultimately confirm most of what we have all grown up to believe over the years.

This is the closest answer so far.

The below is an unmodified answer from Chat GPT. There is a risk with chat GPT that it get’s it’s information from opinions in forums, however in this case I think it’s answered it accurately anyway. Nothing I’ve found online focusses on the SATA port mode and instead focusses on the array creation part which invalidates most information. But Chat GPT has found it somewhere - I think!

RAID mode in an AMD motherboard BIOS does not enable a true hardware RAID controller. Instead, it prepares the system for firmware-assisted RAID (a software-managed RAID solution) and operates fundamentally as a pass-through or metadata management mode. Let’s revisit the analysis with the understanding that the SATA controller is not a hardware RAID controller.

What Actually Happens When RAID Mode Is Enabled Without an Array?

  1. No Hardware RAID Controller:

• The motherboard BIOS or UEFI does not include a dedicated hardware RAID processor. Instead, RAID mode enables firmware features to prepare for RAID, but the underlying disk I/O is still managed by the system CPU.

  1. Individual Disk Exposure:

• If no array is created, RAID mode still exposes individual disks to the operating system, similar to AHCI mode. However, the path for disk commands changes slightly because they are routed through the RAID firmware.

  1. Changes in Command Handling:

• The RAID firmware may add metadata or modify some standard ATA commands, even when an array is not configured. For example:

Disk Identification: The firmware might tag disks as “RAID-capable” or reserve small sectors for RAID metadata.

SMART/Diagnostics: Direct SMART access could be mediated or restricted.

Native Command Queuing (NCQ): This is usually still supported but routed through the firmware.

ZFS in RAID Mode Without a RAID Array

ZFS can technically function with the controller in RAID mode, provided individual disks are visible to the operating system. However, the following considerations apply:

Potential Benefits

  1. Unified Driver Stack:

• RAID mode enables the AMD RAIDXpert2 driver stack, which might improve compatibility if RAID arrays or mixed RAID/standalone configurations are used in the future.

  1. Boot Drive Compatibility:

• RAID mode can simplify boot drive setups if RAID 1 or other configurations are needed for the system drive, while ZFS is used for data drives.

Potential Negatives

  1. Abstraction Layer Overhead:

• Disk commands are routed through the RAID firmware, which can introduce slight performance overhead compared to AHCI mode, even when no array is configured.

  1. Metadata Interference:

• RAID mode may write small amounts of metadata to drives, which could conflict with ZFS metadata or interfere with recovery operations in the event of disk failure.

  1. Limited Low-Level Disk Access:

• Features like SMART, TRIM, and detailed diagnostics may be mediated or blocked, depending on the RAID firmware’s implementation.

  1. Recovery Complexity:

• In cases of disk failure, RAID firmware might obscure ZFS’s ability to directly access or recover raw disk data, complicating troubleshooting or recovery efforts.

Does RAID Mode Add Any Benefit to ZFS in This Case?

From a purely technical perspective, RAID mode does not add any benefit to ZFS unless you have a specific need for AMD’s RAID driver (e.g., for mixed environments or boot configurations). In fact, it can introduce minor drawbacks, such as:

• Potential interference with ZFS’s native features like checksumming and error recovery.

• Slight performance overhead from the firmware layer.

• Possible limitations on advanced disk features (e.g., SMART or TRIM).

Best Practice: Use AHCI Mode

For ZFS to function optimally:

Disable RAID Mode and use AHCI mode to expose individual disks directly to ZFS. This ensures:

• Full control over the disks.

• Direct access to low-level features like SMART and TRIM.

• Minimal overhead in the I/O path.

If RAID mode is enabled by necessity (e.g., for a mixed-use environment or boot drive setup), ensure that:

• No arrays are configured for the disks intended for ZFS.

• The disks are presented individually to the operating system.

Conclusion

RAID mode on an AMD motherboard does not enable a hardware RAID controller but instead engages firmware-level RAID preparation. For ZFS, RAID mode introduces no practical benefits and can impose minor drawbacks. AHCI mode is the recommended configuration for using ZFS effectively with raw individual disks.

I think the above answers my questions near enough. Which re-validates what we all already came to understand over the years, but with supporting information - which is not to do it. It was fun to find out anyway!

Thanks for reading.

Marshalleq

You can get an chatbot to say pretty much whatever you want. Even when you’re not guiding it as such it’s not going to be 100% accurate and it’s insincere to present it as being a possibility.

Any credibility you had has, in my eyes, now been lost. Offering a wall of text from a chat robot as your side of the argument is essentially trolling.

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I’ve said where it came from and it would seem yet again a failure to read as it supports the other side of the argument actually.

I am here to have discourse with humans, not with an algorithm.

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Not worth the metaphorical paper it is written on. Not worth the electricity needed to move the answer from a server somewhere to my machine, much less the untold amounts of energy wasted to get to the point of getting that answer out of the model.

It contributes nothing to the discussion because it’s not reliable… and that’s even before considering that most of these information were already provided in previous replies.

Personally I find it quite disrespectful to ignore answers and post a chatbot replay that affirms basically the same things. You really feel like a troll, so if you aren’t I would suggest trying to understand why you are perceived this way.

Anyway, I won’t invest any more of my time in this thread.