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

Tue Nov 17 14:01:22 UTC 2020
Valeri Galtsev <galtsev at kicp.uchicago.edu>

> On Nov 17, 2020, at 1:07 AM, hw <hw at gc-24.de> wrote:
> 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.

There are advantages in a bleeding edge one can find useful. There is some bleeding too, plausible, so don’t be surprised.


> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos