Unraid and DPO and FUV

[Jetjockey]

Hi Folks.

I'm new to the forum and am just building my first Unraid server. I have done quite a bit of research and realise that the correct hardware is Key....... However....... Was made an offer I couldn't refuse a few days ago and purchased a mobo, processor and 32GB memory at a silly price. The MoBo is an MSI Z77A GD65 with 8 SATA ports and 4 PCI Express slots to take 4 more controller cards. On paper an ideal Motherboard for future expansion. I must say the build quality looks good also, plus it has an Intel network implementation.

 

Its installed and fired up and I am currently Pre clearing 3 disks. I have checked the Sys Log and am getting some error messages though. If I am about to trust my lifes work (Photos, Documents, Movies, Music) to this server, then it has to be right! Do I bin the Motherboard, or do I / can I fix the issues.

 

First I am getting ACPI Namespace Lookup errors. This seems fairly common with several motherboards so I am about to download the latest Bios from MSI. Assuming this does not cure the problem, Can I just turn off ACPI either within the Bios or within Unraid? Will this then cause any problems? Does Unraid actually use the ACPI function?

 

Next, I am showing (during the boot-up phase) a couple of messages to the effect that write cache has been enabled but that DPO and FVO are not supported. This is not peculiar to the MSI Mobo, I have experienced it on two other (very nice) Gigabyte boards. Is this something I should be worried about? What is DPO and FUV? Can this be fixed, or is it a Hardware limitation that cannot be fixed without changing Motherboards?

 

Sorry about the long post, but I only get 2 days home per week and am trying to get this project up and running and finalised whilst juggling a multitude of other stuff at the same time.

 

Thanks in anticipation for any help. 

[itimpi]

Its installed and fired up and I am currently Pre clearing 3 disks. I have checked the Sys Log and am getting some error messages though. If I am about to trust my lifes work (Photos, Documents, Movies, Music) to this server, then it has to be right! Do I bin the Motherboard, or do I / can I fix the issues.

Just a point - unRAID is a fault tolerant system but it is NOT a backup.    Really important files should be backed up elsewhere in case of any sort catastrophic failure on the unRAID system that leads to data loss.

[flintlock1]

I believe that all modern disks with write caches support a way to flush the cache; in SCSI (and SAS) this is the SYNCHRONIZE CACHE SCSI command. Of course this has the usual drawback that it flushes even data that you may not care about and not need to be committed to disk right now. As I discovered yesterday, drives can also support a write option called 'Force Unit Access' (FUA) that bypasses the write cache in order to force what you're writing to be forced to disk. In general FUA is bundled with another feature called 'Disable Page Out' (DPO), which tells the drive that putting the data into cache is not useful.

 

(DPO and FUA can also be used on reads, apparently, but I haven't looked into that at all.)

 

Historically, FUA support has apparently been common and well done in SCSI (and SAS) drives and SAS drivers routinely support it. FUA support in ordinary SATA drives was apparently a chancy thing in the beginning and as a result Linux's SATA driver still defaults to pretending that drives do not support FUA (and I believe DPO) regardless of what the actual drive reports (other OSes may behave similarly). How SATA drives behind a SAS controller behave and how your SAS controller driver treats them is probably an interesting question that you may want to check for yourself if you have such a setup.

[Jetjockey]

Thanks Itimpi. Understand where you are coming from.

 

Thanks flintlock1, that's interesting. So what you are saying is that my WD Reds may well support this function but Unraid will report that they don't. Also, this doesn't appear to be a mission critical feature and that Unraid will work perfectly well without it?

 

Right, if that's all correct, I can move on to the ACPI Namespace errors that are showing up. I am downloading the latest BIOS for the Motherboard now. If that does not fix matters, then I assume that I can turn off the ACPI without hindering or affecting the operation of Unraid??

 

Thanks.

[flintlock1]

You might want to try looking at this post:

 

Check out this post: http://lime-technology.com/forum/index.php?topic=1506.0

 

basically, edit the syslinux.cfg file on your flash drive

 

In it is a line like this:

append initrd=bzroot rootdelay=10

 

Add acpi=off to the end of it so it looks like this and see if it helps

append initrd=bzroot rootdelay=10 acpi=off

[Jetjockey]

Thanks Flintlock1

 

I will try this if the bios upgrade doesn't fix things and will report back.

 

Waiting for a disk pre clear to complete at the mo.

 

Thanks.