CentOS - Jan 2023 - Looking for a RAID1 box

> At Fri, 6 Jan 2023 08:39:22 +0100 CentOS mailing list <centos at
centos.org>
> wrote:
>
>>
>> Hi
>>
>> > I have found a:
>> >
>> > HPE 873830-S01 ProLiant MicroServer Gen10
>> >
>> > for <$300 without drives.'?''?''?'? If
I can believe the seller, it
>> has a AMD
>> > Opteron X3216 Dual-core (2 Core) 1.6GHz and 8GB Installed.
>> >
>> > It has 4 3.5" bays. and 1? "Media" bay?
>> >
>> > https://www.servertechsupply.com/873830-s01/
>> >
>> > this could well be acceptable.'?''?''?'?
Got to find out power
>> draw.'?''?''?'? Looks like
>> > ~40W.
>> >
>> > Any input on issues of OS
install?'?''?''?'? Do I go with separate OS
>> and data
>> > RAID1 sets?
>>
>> I usually do
>>
>> [ 1(+n) RAID1 ]->[ LVM ]->[ XFS ]
>>
>> then you can use LVM to manage different filesystems as required.
>>
>> /boot and/or /boot/efi should be on its own RAID1 with old metadata
>> version but I'm not up to date about how the situation is exactly
with
>> EL9.
>
> It depends on the version of Grub.  Grub V1 needs /boot to be RAID1 with
> old
> metadata (metadata at the *end* of the partition, so Grub just sees a
> plain
> ext2/3/4 file system to find vmlinuz and initrd).  Note: /boot/efi or the
> grub
> fs that Grub2 seems to want cannot be RAID, but you should duplicate the
> partitions across all of the physical disks in the raid set and arange
> some
> other way of "mirroring" them (eg rsync or some such -- does not
need to
> be
> continious, since these file systems don't change continuiously).  I
> believe
> Grub V2 understands raid and LVM, so having a separate /boot raid set
> might
> not be needed.  Things like /boot/efi and grub's on fs still need to
exist
> outside of the raid set and will need "manual" mirroring.
Are you sure that's still true? I've done it that way in the past but it
seems at least with EL8 you can put /boot/efi on md raid1 with metadata
format 1.0. That way the EFI firmware will see it as two independent FAT
filesystems. Only thing you have to be sure is that nothing ever writes to
these filesystems when Linux is not running, otherwise your /boot/efi md
raid will become corrupt.

Can someone who has this running confirm that it works?

Thanks,
Simon
>
>>
>> Simon
>>
>> >
>> > Also HPE is ClearOS.'?''?''?'? I ran
ClearOS6 for years before going
>> with QNAP
>> > turnkey.'?''?''?'? Perhaps current ClearOS
is better, but it does not
>> handle
>> > multi-domain email as I need.'?''?''?'? Or
it did not.'?''?''?'? So I
>> am going to install
>> > my own CentOS variant and iRedMail...
>> >
>> > thanks
>> >
>> >
>> > On 1/5/23 13:08, Jon LaBadie wrote:
>> >> On Thu, Jan 05, 2023 at 08:18:08AM -0500, Robert Moskowitz
wrote:
>> >>> Proliant gen8 does NOT have UEFI.
>> >>>
>> >>> So I think this means I better move up to the gen10...
>> >>>
>> >>
>> >> I'm pleased with my Gen 10+
(Plus).'?''?''?'? Pricer than I thought
>> >> you want.
>> >>
>> >> I like the "no power supply", just an external
brick.
>> >> Quiet.'?''?''?'? I put in a PCI card
to use 2 NVMe sticks, one for
>> >> system and one for /home.'?''?''?'?
You can also boot from an
>> internal
>> >> usb port like a thumb drive permanently installed.
>> >>
>> >> Carriers for 2.5inch SSD drives work fine so with few fans,
>> >> no drive motors, could be quite low power.
>> >>
>> >> Mine acts as email server, local caching DNS server (dnsmasq)
>> >> and Amanda backup server.
>> >>
>> >> Jon
>> >>
>> >
>> >
>> > _______________________________________________
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>> > CentOS at centos.org
>> > https://lists.centos.org/mailman/listinfo/centos
>> >
>>
>>
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>>
>
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Once upon a time, Simon Matter <simon.matter at invoca.ch>
said:
> Are you sure that's still true? I've done it that way in the past
but it
> seems at least with EL8 you can put /boot/efi on md raid1 with metadata
> format 1.0. That way the EFI firmware will see it as two independent FAT
> filesystems. Only thing you have to be sure is that nothing ever writes to
> these filesystems when Linux is not running, otherwise your /boot/efi md
> raid will become corrupt.
> 
> Can someone who has this running confirm that it works?
Yes, that's even how RHEL/Fedora set it up currently I believe.  But
like you say, it only works as long as there's no other OS on the system
and the UEFI firmware itself is never used to change anything on the FS.
It's not entirely clear that most UEFI firmwares would handle a drive
failure correctly either (since it's outside the scope of UEFI), so IIRC
there's been some consideration in Fedora of dropping this support.

And... I'm not sure if GRUB2 handles RAID 1 /boot fully correctly, for
things where it writes to the FS (grubenv updates for "savedefault"
for
example).  But, there's other issues with GRUB2's FS handling anyway, so
this case is probably far down the list.

I think that having RAID 1 for /boot and/or /boot/efi can be helpful
(and I've set it up, definitely not saying "don't do that"),
but has to
be handled with care and possibly (probably?) would need manual
intervention to get booting again after a drive failure or replacement.

-- 
Chris Adams <linux at cmadams.net>