CentOS - Nov 2020 - Intel RST RAID 1, partition tables and UUIDs

I have been having some problems with hardware RAID 1 on the motherboard that I
am running CentOS 7 on. After a BIOS upgrade of the system, I lost the RAID 1
setup and was no longer able to boot the system.

Testdisk revealed that the partition tables had been damaged and because I had
earlier saved information from fdisk, I was able to recreate the partitions.
However, booting into the BIOS and recreating/synchronizing the RAID from one of
the disks (took around 20 hours for 256 GB disks), I again lost the ability the
boot and the partition tables were similarly damaged. Eventually I was able to
boot the system again from one of the two disks and it is now up and running,
now running without RAID.

- Should I expect that the Intel RAID 1 setup changes the partition tables? I
should add that the disks were originally created after the RAID 1 was setup.

- After fooling around with testdisk (and prior to that, parted), it turned out
that I had lost the disk UUID for both disks, they were both set to 000...
Partition UUIDs seemed unchanged from before, including the LUKS partitions. Are
disk UUIDs (not partition UUIDs) not used by Linux since I have not - yet - seen
any effects of the missing disk UUIDs?

Because there seems to be a couple of other issues with the motherboard, I
expect to have it replaced early this week but I am still interested in learning
more.

Thanks.

On Sun, Nov 15, 2020 at 07:49:09PM -0500, H wrote:
>
> I have been having some problems with hardware RAID 1 on the
> motherboard that I am running CentOS 7 on. After a BIOS upgrade of
> the system, I lost the RAID 1 setup and was no longer able to boot
> the system. 
The Intel RST RAID (aka Intel Matrix RAID) is also known as a
fakeraid.  It isn't a hardware RAID, but instead a software RAID that
has a fancy BIOS interface.  I believe that the mdadm tool can examine
the RAID settings, and you can look at /proc/mdstat to see its status,
although from what I remember from previous posts, it's better to just
let the BIOS think it's a JBOD and use the linux software RAID tools
directly. 

-- 
Jonathan Billings <billings at negate.org>

the main advantage I know of for bios fake-raid is that the bios can boot
off either of the two mirrored boot devices.    usually if the sata0 device
has failed, the BIOS isn't smart enough to boot from sata1

the only other reason is if you're running MS Windows desktop which
can't
do mirroring on its own

On Mon, Nov 16, 2020 at 10:23 AM Jonathan Billings <billings at
negate.org>
wrote:
> On Sun, Nov 15, 2020 at 07:49:09PM -0500, H wrote:
> >
> > I have been having some problems with hardware RAID 1 on the
> > motherboard that I am running CentOS 7 on. After a BIOS upgrade of
> > the system, I lost the RAID 1 setup and was no longer able to boot
> > the system.
>
> The Intel RST RAID (aka Intel Matrix RAID) is also known as a
> fakeraid.  It isn't a hardware RAID, but instead a software RAID that
> has a fancy BIOS interface.  I believe that the mdadm tool can examine
> the RAID settings, and you can look at /proc/mdstat to see its status,
> although from what I remember from previous posts, it's better to just
> let the BIOS think it's a JBOD and use the linux software RAID tools
> directly.
>
> --
> Jonathan Billings <billings at negate.org>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
>

-- 
-john r pierce
  recycling used bits in santa cruz

On 11/16/2020 01:23 PM, Jonathan Billings wrote:
> On Sun, Nov 15, 2020 at 07:49:09PM -0500, H wrote:
>> I have been having some problems with hardware RAID 1 on the
>> motherboard that I am running CentOS 7 on. After a BIOS upgrade of
>> the system, I lost the RAID 1 setup and was no longer able to boot
>> the system. 
> The Intel RST RAID (aka Intel Matrix RAID) is also known as a
> fakeraid.  It isn't a hardware RAID, but instead a software RAID that
> has a fancy BIOS interface.  I believe that the mdadm tool can examine
> the RAID settings, and you can look at /proc/mdstat to see its status,
> although from what I remember from previous posts, it's better to just
> let the BIOS think it's a JBOD and use the linux software RAID tools
> directly. 
>
I see, thank you. Right now I am running off one of the disks because of the
mishap, I am also waiting for a systemboard replacement at which time I can
decided whether to go with Linux software RAID, ie mdadm, or back to the Intel
BIOS RAID.

The latter lacks any progress indicators in BIOS when rebuilding an array which
took around 20 hours for a 256 GB RAID 1 setup and it is annoying not to know
the status of the rebuild etc. Could mdadm in a command window helped me answer
that question?

Also, it seemed that the BIOS RAID damaged the partition table on the disks -
should I expect that this happens? My guess would be no but what do I know...