Re: ASRock A785GMH/128M fails to find devices when in RAID mode and disks are present

[Xen]

Andrei Borzenkov schreef op 30-07-2016 20:49:
> 29.07.2016 17:29, Xen пишет:
> > Just want to report that I have a motherboard (A785GMH/128M) that will
> > fail to boot the moment a RAID disk is present.
>
> Is it EFI or legacy BIOS?

Legacy.


> So what exactly "normal" means here? Do you have any evidence 
> bootloader
> on this DVD can see disks?

I will have to check, I didn't get as far (sorry, yet). Will do so in a 
minute.


> Usually add-on controllers have boot ROM that needs to be activated on
> power on; so the very first sugestion would be to verify that this is
> the case. Do you see array in the list of boot devices in BIOS setup?

Yes, this particular motherboard is so.... well all of them hide the 
real disks I guess and show only "arrays", sometimes those arrays are 
single disk arrays.

I have a Gigabyte AM2 motherboard that ...I believe will treat those 
disks as "single disk" and automatically create an array out of them 
without configuration, not sure. And that mobo has support for "raid 5 
and 6" (I mean sata 5 and 6) not being RAID.

I will boot this mobo from DVD now with two "single disks" present, brb.

Back.

Of course in Linux even if you do activate (dmraid) the default is that 
the original devices remain visible.

I have put one of two disks.... actually I did not do anything, for some 
reason the BIOS took one disk and put it in JBOD, while the other was 
not added.

# dmraid -r
ERROR: pdc: identifying /dev/sda, magic_0: 0xe1e2e3e4/0x8c130729, 
magic_1: 0xd9dadbdc/0x0, total_disks: 0
/dev/sdb: pdc, "pdc_dgddfbecib", stripe, ok, 1953124992 sectors, data@ 0

The first disk is the one that wasn't added. It might have an identifier 
on it, I don't know. This disk is actually not shown (at this point) as 
a boot device in BIOS.

The second disk is accessible as sdb, and I don't know why it says 
stripe, it is the JBOD disk.

In /dev:

brw-rw----  1 root    disk      8,  16 Jul 30  2016 sdb

dmsetup table:

pdc_dgddfbecib: 0 1953124992 linear 8:16 0

Clearly, just a linear mapping the way it is intended.

If I was now trying to boot from it, I would most likely only see this 
"JBOD" array as a choice to boot from. To the BIOS it is that.

The other one is not visible to the BIOS.

So yes, the arrays do work.

But actually you asked the /bootloader/ of this DVD.

I'm sure it doesn't care about any disks (or arrays) as it just tries to 
load its own DVD.



I don't know how Grub responds to a 'functioning' motherboard when 
someone would try to boot from e.g. a striped disk. Does it see the 
array? I have seen a suggestion somewhere of adding this array to 
device.map.

I was going to try to see what would happen if I used a device.map to 
install grub on the array:

# grub-mkdevicemap

# cat device.map
(hd0)   /dev/disk/by-id/ata-WDC_WD7500BPKX-00HPJT0_WD-WX81AB574LVH
(hd1)   /dev/disk/by-id/ata-ST1000LM024_HN-M101MBB_S2ZWJ9DG703561
(hd2)   /dev/mapper/pdc_dgddfbecib

# /usr/local/sbin/grub-install /dev/mapper/pdc_dgddfbecib
Installing for i386-pc platform.
  Found duplicate PV fEGbBntbIprL7ym22b1rQhr9i5Qwlqz7: using 
/dev/mapper/pdc_dgddfbecib not /dev/sdb
  Using duplicate PV /dev/mapper/pdc_dgddfbecib from subsystem DM, 
ignoring /dev/sdb
  Found duplicate PV fEGbBntbIprL7ym22b1rQhr9i5Qwlqz7: using 
/dev/mapper/pdc_dgddfbecib not /dev/sdb
  Using duplicate PV /dev/mapper/pdc_dgddfbecib from subsystem DM, 
ignoring /dev/sdb
/usr/local/sbin/grub-install: error: cannot find a GRUB drive for 
/dev/mapper/pdc_dgddfbecib.  Check your device.map.

So something isn't working. I don't even know if you *can* use Grub2 to 
boot off an array these days, without using Grub Legacy.