new array not starting

new array not starting

[Robin Bowes]

Hi,

I've just done an FC6 install on to a system with 2 x 250GB disks and 8
x 500GB disks. /dev/md0 is a 100MB mirror mounted as boot, and /dev/md1
is another mirror using the rest of the disks and is assigned to an LVM
PV/VG with LVs created for various system partitions.

After fun and games with grub (0.97 only supports up to 8 disks - I had
to patch grub to support up to 16 disks) I got the server to boot.

I then configured /dev/md2 as an 8 disk RAID6 array using the 8 x 500GB
disks using the whole of each disk for the array, i.e. no partitions.

This is the command I used to create the array:

mdadm --create /dev/md2 --raid-devices=8 --level=6 --auto=yes /dev/sdc
/dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj

When the array havd finished syncing, I rebooted the server.

However, /dev/md2 did not restart.

If I try to start the array manually:

# mdadm --assemble --auto=yes  /dev/md2 /dev/hdc /dev/hdd /dev/hde
/dev/hdf /dev/hdg /dev/hdh /dev/hdi /dev/hdj
mdadm: cannot open device /dev/hdc: No such file or directory
mdadm: /dev/hdc has no superblock - assembly aborted

What's going on here? No superblock? Doesn't that get written when the
array is created?

Am I doing this right?

Thanks,

R.

Re: new array not starting

[Robin Bowes]

Robin Bowes wrote:
> 
> If I try to start the array manually:
> 
> # mdadm --assemble --auto=yes  /dev/md2 /dev/hdc /dev/hdd /dev/hde
> /dev/hdf /dev/hdg /dev/hdh /dev/hdi /dev/hdj
> mdadm: cannot open device /dev/hdc: No such file or directory
> mdadm: /dev/hdc has no superblock - assembly aborted
> 
> What's going on here? No superblock? Doesn't that get written when the
> array is created?
> 
> Am I doing this right?

SATA disks? hdc? Duh!

This worked:

# mdadm --assemble --auto=yes  /dev/md2 /dev/sdc /dev/sdd /dev/sde
/dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj
mdadm: /dev/md2 has been started with 8 drives.

However, I'm not sure why it didn't start automatically at boot. Do I
need to put it in /etc/mdadm.conf for it to star automatically? I
thought md start all arrays it found at a start up?

R.

Re: new array not starting

[Robin Bowes]

Robin Bowes wrote:
> This worked:
> 
> # mdadm --assemble --auto=yes  /dev/md2 /dev/sdc /dev/sdd /dev/sde
> /dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj
> mdadm: /dev/md2 has been started with 8 drives.
> 
> However, I'm not sure why it didn't start automatically at boot. Do I
> need to put it in /etc/mdadm.conf for it to star automatically? I
> thought md start all arrays it found at a start up?

OK, I put /dev/md2 in /etc/mdadm.conf and it didn't make any difference.

This is mdadm.conf (uuids are on same line as ARRAY):

DEVICE partitions
ARRAY /dev/md1 level=raid1 num-devices=2
uuid=300c1309:53d26470:64ac883f:2e3de671
ARRAY /dev/md0 level=raid1 num-devices=2
uuid=89649359:d89365a6:0192407d:e0e399a3
ARRAY /dev/md2 level=raid6 num-devices=8
UUID=68c2ea69:a30c3cb0:9af9f0b8:1300276b

I saw an error fly by as the server was booting saying "/dev/md2 not found".

Do I need to create this device manually?

R.

Re: new array not starting

[Robin Bowes]

Robin Bowes wrote:
> Robin Bowes wrote:
>> This worked:
>>
>> # mdadm --assemble --auto=yes  /dev/md2 /dev/sdc /dev/sdd /dev/sde
>> /dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj
>> mdadm: /dev/md2 has been started with 8 drives.
>>
>> However, I'm not sure why it didn't start automatically at boot. Do I
>> need to put it in /etc/mdadm.conf for it to star automatically? I
>> thought md start all arrays it found at a start up?
> 
> OK, I put /dev/md2 in /etc/mdadm.conf and it didn't make any difference.
> 
> This is mdadm.conf (uuids are on same line as ARRAY):
> 
> DEVICE partitions
> ARRAY /dev/md1 level=raid1 num-devices=2
> uuid=300c1309:53d26470:64ac883f:2e3de671
> ARRAY /dev/md0 level=raid1 num-devices=2
> uuid=89649359:d89365a6:0192407d:e0e399a3
> ARRAY /dev/md2 level=raid6 num-devices=8
> UUID=68c2ea69:a30c3cb0:9af9f0b8:1300276b
> 
> I saw an error fly by as the server was booting saying "/dev/md2 not found".
> 
> Do I need to create this device manually?

Well, at the risk of having a complete conversation with myself, I've
created partitions of type "fd" on each disk and re-created the array
out of the partitions instead of the whole disk.

mdadm --create /dev/md2 --auto=yes --raid-devices=8 --level=6 /dev/sdc1
/dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdg1 /dev/sdh1 /dev/sdi1 /dev/sdj1

I'm hoping this will enable the array to be auto-detected and started at
boot.

R.

Re: new array not starting

[Robin Bowes]

Robin Bowes wrote:
> 
> Well, at the risk of having a complete conversation with myself, I've
> created partitions of type "fd" on each disk and re-created the array
> out of the partitions instead of the whole disk.
> 
> mdadm --create /dev/md2 --auto=yes --raid-devices=8 --level=6 /dev/sdc1
> /dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdg1 /dev/sdh1 /dev/sdi1 /dev/sdj1
> 
> I'm hoping this will enable the array to be auto-detected and started at
> boot.

That seemed to do the trick.

I left the array to build overnight and rebooted this morning, and
/dev/md2 started normally.

R.

Re: new array not starting

[Bill Davidsen]

Robin Bowes wrote:

>Robin Bowes wrote:
>  
>
>>Robin Bowes wrote:
>>    
>>
>>>This worked:
>>>
>>># mdadm --assemble --auto=yes  /dev/md2 /dev/sdc /dev/sdd /dev/sde
>>>/dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj
>>>mdadm: /dev/md2 has been started with 8 drives.
>>>
>>>However, I'm not sure why it didn't start automatically at boot. Do I
>>>need to put it in /etc/mdadm.conf for it to star automatically? I
>>>thought md start all arrays it found at a start up?
>>>      
>>>
>>OK, I put /dev/md2 in /etc/mdadm.conf and it didn't make any difference.
>>
>>This is mdadm.conf (uuids are on same line as ARRAY):
>>
>>DEVICE partitions
>>ARRAY /dev/md1 level=raid1 num-devices=2
>>uuid=300c1309:53d26470:64ac883f:2e3de671
>>ARRAY /dev/md0 level=raid1 num-devices=2
>>uuid=89649359:d89365a6:0192407d:e0e399a3
>>ARRAY /dev/md2 level=raid6 num-devices=8
>>UUID=68c2ea69:a30c3cb0:9af9f0b8:1300276b
>>
>>I saw an error fly by as the server was booting saying "/dev/md2 not found".
>>
>>Do I need to create this device manually?
>>    
>>
>
>Well, at the risk of having a complete conversation with myself, I've
>created partitions of type "fd" on each disk and re-created the array
>out of the partitions instead of the whole disk.
>
>mdadm --create /dev/md2 --auto=yes --raid-devices=8 --level=6 /dev/sdc1
>/dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdg1 /dev/sdh1 /dev/sdi1 /dev/sdj1
>
>I'm hoping this will enable the array to be auto-detected and started at
>boot.
>  
>
I'm guessing that whole devices don't get scanned when "partitions" is 
used. There was a fix for incorrect partition tables being used on whole 
drives, and perhaps that makes the whole device get ignored, or perhaps 
it never worked. Perhaps there's an interaction with LVM, the more 
complex you make your setup the greater the chance for learning experiences.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

Re: new array not starting

[Richard Scobie]

Robin Bowes wrote:
> Robin Bowes wrote:
> 
>>This worked:
>>
>># mdadm --assemble --auto=yes  /dev/md2 /dev/sdc /dev/sdd /dev/sde
>>/dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj
>>mdadm: /dev/md2 has been started with 8 drives.
>>
>>However, I'm not sure why it didn't start automatically at boot. Do I
>>need to put it in /etc/mdadm.conf for it to star automatically? I
>>thought md start all arrays it found at a start up?
> 
> 
> OK, I put /dev/md2 in /etc/mdadm.conf and it didn't make any difference.
> 
> This is mdadm.conf (uuids are on same line as ARRAY):
> 
> DEVICE partitions
> ARRAY /dev/md1 level=raid1 num-devices=2
> uuid=300c1309:53d26470:64ac883f:2e3de671
> ARRAY /dev/md0 level=raid1 num-devices=2
> uuid=89649359:d89365a6:0192407d:e0e399a3
> ARRAY /dev/md2 level=raid6 num-devices=8
> UUID=68c2ea69:a30c3cb0:9af9f0b8:1300276b
> 
> I saw an error fly by as the server was booting saying "/dev/md2 not found".
> 
> Do I need to create this device manually?

Try adding

auto=part

at the end of the /dev/md2 entry.

Regards,

Richard