Re: mdadm -A /dev/md3 fails

I apologize for the really late answer, it looks like this message never
left my laptop.

On Mon, Sep 09, 2002 at 01:18:52AM -0700, Derek Vadala wrote:

On Mon, 9 Sep 2002, Marc MERLIN wrote:

quoted

gargamel:/etc/mdadm# mdadm -A  -v /dev/md3
mdadm: No identity information available for /dev/md3 - cannot assemble.

Try mdadm -Avs /dev/md3

-s or --scan tells mdadm to use the config file.

Yep, that worked fine, thanks.

On Mon, Sep 09, 2002 at 09:07:03PM +1000, Neil Brown wrote:

On Monday September 9, marc_news@merlins.org wrote:

quoted

On Mon, Sep 09, 2002 at 04:20:14PM +1000, Neil Brown wrote:

quoted

That is part of the reason that I wrote mdadm.  It can do the right
thing for you.

Apparently it can, but I'm having issues with it:

My conf file says:
DEVICE /dev/scsi/host*/bus*/target*/lun*/part*
ARRAY /dev/md3 level=raid5 num-devices=7 UUID=7f69d69c:2d523219:4f3d1ea7:9b7f4057 devices=/dev/scsi/host3/bus0/target8/lun0/part1,/dev/scsi/host3/bus0/target9/lun0/part1,/dev/scsi/host3/bus0/target10/lun0/part1,/dev/scsi/host3/bus0/target11/lun0/part1,/dev/scsi/host3/bus0/target12/lun0/part1,/dev/scsi/host3/bus0/target13/lun0/part1,/dev/scsi/host3/bus0/target14/lun0/part1

gargamel:/etc/mdadm# mdadm -A  -v /dev/md3
mdadm: No identity information available for /dev/md3 - cannot assemble.

Any idea why 
mdadm -A -v /dev/md3 doesn't work?

As Derek says, add "--scan" to tell it that it is allowed to look in
the config file.
Also, get rid of the "devices=...." part of the ARRAY line or it will
fail if any of the devices change address.

quoted

Am I supposed to actually start the device with
mdadm -A  -v /dev/md3 /dev/scsi/host3/bus0/target*/lun0/part1 ?

That would probably work..

 
Yep, it works.
 

quoted

or
mdadm -A  -v -u 7f69d69c:2d523219:4f3d1ea7:9b7f4057 /dev/md3 ?

That wouldn't.  Would would need to to mdadm where the devices are:

Actuallly, it does work, that's why I listed it.
gargamel:/etc/mdadm# mdadm -A  -v -u 7f69d69c:2d523219:4f3d1ea7:9b7f4057 /dev/md3
mdadm: looking for devices for /dev/md3
mdadm: /dev/scsi/host3/bus0/target9/lun0/part1 is identified as a member of /dev/md3, slot 1.
mdadm: /dev/scsi/host3/bus0/target8/lun0/part1 is identified as a member of /dev/md3, slot 0.
mdadm: /dev/scsi/host3/bus0/target14/lun0/part1 is identified as a member of /dev/md3, slot 6.
mdadm: /dev/scsi/host3/bus0/target13/lun0/part1 is identified as a member of /dev/md3, slot 5.
mdadm: /dev/scsi/host3/bus0/target12/lun0/part1 is identified as a member of /dev/md3, slot 4.
mdadm: /dev/scsi/host3/bus0/target11/lun0/part1 is identified as a member of /dev/md3, slot 3.
mdadm: /dev/scsi/host3/bus0/target10/lun0/part1 is identified as a member of /dev/md3, slot 2.
mdadm: /dev/scsi/host0/bus0/target4/lun0/part3 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target4/lun0/part2 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target4/lun0/part1 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target3/lun0/part3 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target3/lun0/part2 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target3/lun0/part1 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target10/lun0/part3 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target10/lun0/part2 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target10/lun0/part1 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target1/lun0/part3 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target1/lun0/part2 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target1/lun0/part1 has wrong uuid.
mdadm: no RAID superblock on /dev/scsi/host0/bus0/target0/lun0/part4
mdadm: /dev/scsi/host0/bus0/target0/lun0/part4 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target0/lun0/part3 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target0/lun0/part2 has wrong uuid.
mdadm: /dev/scsi/host0/bus0/target0/lun0/part1 has wrong uuid.
mdadm: added /dev/scsi/host3/bus0/target9/lun0/part1 to /dev/md3 as 1
mdadm: added /dev/scsi/host3/bus0/target10/lun0/part1 to /dev/md3 as 2
mdadm: added /dev/scsi/host3/bus0/target11/lun0/part1 to /dev/md3 as 3
mdadm: added /dev/scsi/host3/bus0/target12/lun0/part1 to /dev/md3 as 4
mdadm: added /dev/scsi/host3/bus0/target13/lun0/part1 to /dev/md3 as 5
mdadm: added /dev/scsi/host3/bus0/target14/lun0/part1 to /dev/md3 as 6
mdadm: added /dev/scsi/host3/bus0/target8/lun0/part1 to /dev/md3 as 0
mdadm: /dev/md3 has been started with 7 drives.

mdadm -A  -v -u 7f69d69c:2d523219:4f3d1ea7:9b7f4057 /dev/md3 /dev/disk/*/part*
would work.

 
I think it worked  without because I already had a  DEVICES line that listed
that in the config file.

quoted

(I thought mdadm would get that data from the config file)

Only when you tell it to.  If that isn't clear from a second reading
of the man page, I would appreciate suggestions on how to make it more
clear.

It is there, although that didn't sync in my brain at my first readings.
I think  it's just  very counter  intuitive that you  have to  provide a
command line option to use the config file.
If I  put something  in the  config file, I  expect it  to be  picked up
without giving any special command line option.
Would you consider making mdadm read anything in mdadm.conf by default?

On Mon, Sep 09, 2002 at 09:11:18PM +1000, Neil Brown wrote:

On Sunday September 8, marc_news@merlins.org wrote:

quoted

That said, the problem occurs both with the kernel autorun and raidstart:
when I load the qla1280 module, the drives get detected, md wakes up and
tries to create md3 since the partitions have type 0xfd, and fails in the
same way:
(...)
kernel:  /dev/scsi/host3/bus0/target13/lun0: p1
kernel: SCSI device sdl: 354600001 512-byte hdwr sectors
kernel:  /dev/scsi/host3/bus0/target14/lun0: p1
kernel:  [events: 00000002]
kernel: md: could not lock sdm1, zero-size? Marking faulty.
(...)

I'm not sure what exactly is going on here, but it isn't regular
auto-detect. That *only* happens at boot time.  Never after module
load.

 
Interesting it would be separate code. Thanks for the info.
 

quoted

Is the kernel autorun code going to be fixed too or will I need to use mdadm
for the forseable future?

I use and recommend mdadm to all non-root devices.  For a raid
containing the root filesystem I use kernel parameters:
   md=0,/dev/xxxx,/dev/yyyy

Good to know, thanks.

though in 2.6, I suspect that initramfs will mean that mdadm is the
best choice for that too.  Don't do in kernel-space that which can
effectively and efficiently be done in user-space.

Right :-)

Thanks for the answers.
Marc
-- 
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