[CentOS] Intel RST RAID 1, partition tables and UUIDs

Tue Nov 17 07:07:50 UTC 2020
hw <hw at gc-24.de>

On Mon, 2020-11-16 at 18:06 -0500, H wrote:
> 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...

I'd use software raid rather the fakeraid.  One of the advantages is that
you are not limited to the mainboard and can use the disks in another machine
if you need to.  If you need to replace the board, you are not limited to
one that provides a compatible fakeraid.

Using software raid with mdadm will give you indication about the progress
of rebuilds and checks by looking at /proc/mdstat, and you can automatically
get an email in case a disk fails if so configured.  Being informed about
disk failures is relevant.

I've used Linux software raid for at least 20 years and never had any problems
with it other than questionable performance disadvantages compared to hardware
raid.  When a disk fails just replace it, and I've recently found that it
can be impossible to get a rebuild started with hardware raid, which makes it
virtually useless.

I've never used the (Intel) fakeraid.  Why would I?

If you don't require Centos, you could go for Fedora instead.  Fedora has btrfs
as default file system now which has software raid built-in, and Fedora can have
advantages over Centos.