On 10/4/19 12:28 AM, Allan wrote:
> På Thu, 3 Oct 2019 07:38:05 -0500
> Valeri Galtsev
> <galtsev@xxxxxxxxxxxxxxxxx> skrev:
>>> On Oct 3, 2019, at 6:24 AM, Günther J. Niederwimmer
>>> <gjn@xxxxxxxxxxx> wrote:
>>>
>>>
>>> 07:00.0 Serial Attached SCSI controller [0107]: Intel Corporation
>>> C602 chipset 4-Port SATA Storage Control Unit [8086:1d6b] (rev 06)?
>>>
>>> what is the Problem with this chipset and why it is no longer
>>> supported ??
>>
>> My impression is that you have it set to “RAID” instead of “AHCI” in
>> BIOS. Switch in BIOS its operation to AHCI, you will see attached
>> drives. Configure these drives as software RAID.
>
> Of course he set it to RAID. He wouldn't be able to boot his raid, if he
> set it to AHCI. If set to AHCI, it would require an extra disk to boot
> the system.
>
>> As a matter of fact neither of fake RAID cards were ever supported by
>> systems I know of (excluding MS Windows) as RAID cards. That is where
>> jargon “fake RAID” widely used by Linux Folks comes from.
>
> Really ? You have really never heard of this small company called Intel,
> whos chipset have been able to boot Linux in RAID mode for a very long
> time ?
>
>> System board manufacturers (motherboard is common jargon for system
>> board for over 20 years) share their part in the spreading of fake
>> RAID chips. Fake RAID chip is cheap (pun intended), so adding it to
>> system board does not increase its cost much, but increases it
>> apparent value in eyer of uninformed (I should say ignorant) mass
>> consumer. It is probably time to call garbage (fake RAID) garbage and
>> not expect from it to behave as real RAID (hardware RAID), and
>> definitely not put blame on the system for garbage hardware being
>> garbage hardware.
>
> You are right, a BIOS chip is really very cheap, and that is all that
> the chipset needs to be able to boot in RAID mode on the existing AHCI
> controllers. There is no raid "card" in these systems - aka no special
> extra raid cpu to control anything.
> All the RAID BIOS does is boot the system to load GRUB ( and maybe GRUB
> uses the same BIOS INT13H service to load the kernel).
> After that, kernel drivers take over - and that is MDADM doing the rest
> of the job, as Intel RAID bios is MDADM compatible.>
> Call it FAKE raid, call it BIOS raid or whatever - it is in fact just a
> Linux software mdadm raid - with the added ability to boot directly from
> the BIOS. I don't see any reason to call this a bad solution or
> unstable in any way more than what mdadm is.
You are wrong. Mdraid (mdadm is only a tool for mdraid) is SOFTWARE
RAID, to create RAID system of regular or AHCI chipset. No part of
mdraid uses BIOS, it is all in kernel/driver.
What you described is actually "dmraid" (discover, configure and
activate software (ATA)RAID ). Dmraid is just an interface for fakeRAID
BIOS to work, and bugs in fakeRAID BIOSes (for which firmare updates
barely exist) are the reason (some) fakeRAID chipsets are removed from
kernel.
>
> I have myself a small desktop/server system here running for almost 7
> years according to SMART on my disks - booting from such a Intel Z77
> chipset to a mdadm raid 5.
>
> I do run Fedora on this system as RH most likely have removed my chipset
> from Centos 8 too.
>
> Allan.
>
>
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--
Ljubomir Ljubojevic
(Love is in the Air)
PL Computers
Serbia, Europe
StarOS, Mikrotik and CentOS/RHEL/Linux consultant
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