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

> 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.

Valeri
> 
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On Tue, 2020-11-17 at 08:01 -0600, Valeri Galtsev wrote:
> 
> > On Nov 17, 2020, at 1:07 AM, hw <hw at gc-24.de> wrote:
> [...]
> > 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.
There is bleeding with Centos 7, too, and Centos 8 is probably no different.
One can always be surprised.

I'm not so much referring to bleeding but advantages like packages being
available
in Fedora that aren't available in Centos.  And not being able to upgrade a
distribution when a new release comes out is a killer for Centos since there are
things in Centos 8 that make me wonder why I shouldn't go for Fedora right
away. At
least I have the goodies when I do that.

But then, there are now things in Fedora that make we wonder if I should switch
to
arch.  Like how retarded is it to forcefully enable swapping to RAM by default.
Either you have plenty RAM and swapping has no disadvantages, or you don't
and
swapping to RAM makes it only worse.  I can see that it might have an advantages
for when you don't create a swap partition, but that's already a bad
idea in the
first place unless you have special requirements that are far from any default.
I don't even dare wondering if it can get any more stupid, because
unfortunately,
there is no limit to stupidity and the only thing helps against it is more
stupidity.

And systemd ursurping the functionality of crond?  The last thing we need is
systemd to become even more cryptic by that --- and how can I check if I am
getting
an email when a failed disk is detected, or when errors are being detected by
raid-check?  I can do that with crond, but not with systemd.

> On Nov 18, 2020, at 2:51 AM, hw <hw at gc-24.de> wrote:
> 
> On Tue, 2020-11-17 at 08:01 -0600, Valeri Galtsev wrote:
>> 
>>> On Nov 17, 2020, at 1:07 AM, hw <hw at gc-24.de> wrote:
>> [...]
>>> 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.
> 
> There is bleeding with Centos 7, too, and Centos 8 is probably no
different.
> One can always be surprised.
And that is why my servers run FreeBSD. But when I switched from Fedora to
CentOS (quite a while back), it made noticeable difference.

Valeri
> I'm not so much referring to bleeding but advantages like packages
being available
> in Fedora that aren't available in Centos.  And not being able to
upgrade a
> distribution when a new release comes out is a killer for Centos since
there are
> things in Centos 8 that make me wonder why I shouldn't go for Fedora
right away. At
> least I have the goodies when I do that.
And that is designed into the way distributions are maintained.

Some of them are like ?sliding release?, like Fedora, Debian? And with those you
often get surprises just upon routine update something breaks, as package is
replaced with higher version which has different internals. But these are a
charm to ?upgrade? to next release. One can also mention FreeBSD and MacOS as
being close to this, IMHO.

Others are ?Enterprise? very long life. They are being patched by back porting
fixes (very effort consuming), but they mostly ?unchanged? packages internal
wise, so during 10 years of such system?s life cycle, it is only rarely you may
have things broken. But when it comes to life cycle end, you effectively have to
build new system, as virtually neither of software packages can just step up
from release 10years old to todays. You effectively do at once all you did for
10 years of "sliding release? system. Examples of this style are: RedHat
Enterprise, CentOS (?binary replica? of the former). With all bad one can say
about Microsoft, I would mention MS Windows system on which something you
install when it release, will still work when the system maintenance ends 10
years later.

So, it is one?s choice, which style of system to install and maintain. I for one
chose CentOS for number crunchers and workstations, which takes less of my time
to maintain (but FreeBSD for servers, but that is different story). Your choice
appears to be different, and we both are right in our choices based of our
goals.
> But then, there are now things in Fedora that make we wonder if I should
switch to
> arch.  Like how retarded is it to forcefully enable swapping to RAM by
default.
> Either you have plenty RAM and swapping has no disadvantages, or you
don't and
> swapping to RAM makes it only worse.  I can see that it might have an
advantages
> for when you don't create a swap partition, but that's already a
bad idea in the
> first place unless you have special requirements that are far from any
default.
> I don't even dare wondering if it can get any more stupid, because
unfortunately,
> there is no limit to stupidity and the only thing helps against it is more
stupidity.
> 
> And systemd ursurping the functionality of crond?  The last thing we need
is
> systemd to become even more cryptic by that --- and how can I check if I am
getting
> an email when a failed disk is detected, or when errors are being detected
by
> raid-check?  I can do that with crond, but not with systemd.
Systemd has resembling portion of code in mainstream Linux kernel (I bet experts
will correct me where I?m wrong). You can try to go with systemd-free Linux
distro like devuan (fork of Debian that happened when Debian went systemd way).
Or you can try one of BSD descendants, which being such are closer to original
UNIX philosophy: FreeBSD, NetBSD, OpenBSD (and variety of others standing quite
close to these, or slightly more apart, your duckduckgo search will be as good
as mine).

Valeri
> 
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