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Old 04-28-2012, 05:33 PM   #1
sewerurchin
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Registered: Apr 2012
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Disk label / RAID strangeness


Hi,
I have two 1.5TB disks (/dev/sda & /dev/sdb) in a RAID 1 configuration set up on a Kubuntu 12.04 system. The RAID device is broken into 9 partitions, md5 through md13 and AFAIK I set them all up in the same way. When I run gparted, sda & sdb are in the list of disks, but so is /dev/md5. And in the xterm that I ran gparted from I get:

/dev/md5: unrecognised disk label

The disk maps displayed by gparted look correct.

Ok. So then I run 'parted -l' to get more info and I get this:

Model: ATA ST31500341AS (scsi)
Disk /dev/sda: 1500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
1 32.3kB 161GB 161GB primary ext3 raid
2 161GB 322GB 161GB primary ext3 raid
3 322GB 483GB 161GB primary ext3 raid
4 483GB 1500GB 1017GB extended
5 483GB 644GB 161GB logical ext3
6 644GB 805GB 161GB logical ext3 raid
7 805GB 966GB 161GB logical ext3 raid
8 966GB 1127GB 161GB logical ext3 raid
9 1127GB 1289GB 161GB logical ext3 raid
10 1289GB 1450GB 161GB logical ext3 raid
11 1450GB 1500GB 50.7GB logical ext3 raid

Model: ATA ST31500341AS (scsi)
Disk /dev/sdb: 1500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
1 32.3kB 161GB 161GB primary ext3 raid
2 161GB 322GB 161GB primary ext3 raid
3 322GB 483GB 161GB primary ext3 raid
4 483GB 1500GB 1017GB extended
5 483GB 644GB 161GB logical ext3 raid
6 644GB 805GB 161GB logical ext3 raid
7 805GB 966GB 161GB logical ext3 raid
8 966GB 1127GB 161GB logical ext3 raid
9 1127GB 1289GB 161GB logical ext3 raid
10 1289GB 1450GB 161GB logical ext3 raid
11 1450GB 1500GB 50.7GB logical ext3 raid

Error: /dev/md5: unrecognised disk label
Error: /dev/md8: unrecognised disk label
Error: /dev/md9: unrecognised disk label
Error: /dev/md7: unrecognised disk label
Error: /dev/md11: unrecognised disk label
Error: /dev/md10: unrecognised disk label

Model: Linux Software RAID Array (md)
Disk /dev/md13: 161GB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number Start End Size File system Flags
1 0.00B 161GB 161GB ext3

Error: /dev/md14: unrecognised disk label
Error: /dev/md12: unrecognised disk label
Error: /dev/md6: unrecognised disk label

All that does is confuse me even more. Can someone please offer an explanation as to why the output from these two commands seem to be showing two different and (I think) incorrect things? What should the output look like?

Tx
 
Old 05-02-2012, 12:37 AM   #2
lazardo
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'parted' is looking at every block device it finds, regardless if it is actually a physical disk.

'fdisk' and 'sfdisk' will give similar errors if you don't specify which device(s) you want to see.

Cheers,
 
Old 05-02-2012, 09:25 AM   #3
sewerurchin
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Registered: Apr 2012
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That's part of what is confusing me. Gparted only show five devices, sda - d and md5. Why not the other md devices? Parted says that all of the md devices have bad disk labels - except md13. Why md13? Maybe all of the md devices are supposed to have disk labels or maybe none of them are or maybe it doesn't matter. I just don't know. So I'm not sure whether I should somehow change them so that they all look the same or what. Everything seems to be running OK without any errors, so what do you think that I should do?
 
Old 05-03-2012, 12:37 AM   #4
lazardo
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What question are you trying to answer? 'parted' is a disk partitioning tool, but not as good at reporting, instead try these to check things out:

cat /proc/partitions
cat /proc/mdstat
sudo fdisk -l /dev/sda /dev/sdb

Cheers,
 
Old 05-03-2012, 12:10 PM   #5
sewerurchin
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Ok, here are my questions:

- When I run 'gparted' it lists five devices (sda,sdb,sdc,sdd,md5) Why five? I have nine md devices. I understand the 'gparted' is a partitioning tool, but it should at least give me a correct list of the devices that I can partition. Seems to me that either all of the md partitions should be listed or none of them should.

- When 'gparted' starts up, it displays the error "/dev/md5: unrecognised disk label". Is there something wrong with the way that "/dev/md5" is set up? Should I be concerned that it seems to have found a problem with one aspect of one of my RAID devices?

- When I run 'parted -l' it "lists partition layout on all block devices". It does so for the four sd devices - that's good'. It then says 'unrecognised disk label" on 8 of the 9 md devices. The ninth one is displayed like this:

Model: Linux Software RAID Array (md)
Disk /dev/md13: 161GB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number Start End Size File system Flags
1 0.00B 161GB 161GB ext3

Why? Is there something wrong with the way the other 8 md devices are set up? Is it something that I need to fix?

It's the inconsistency that bothers me. I worry that either I did something wrong when I set everything up or that something has gone wrong in the recent past. It might not be something critical, but it still bothers me.

Thanks
 
Old 05-07-2012, 11:39 PM   #6
lazardo
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Rather than getting stuck on particular linux utility behaviors that are not useful, if '/proc/mdstat' md device components agree with information in '/proc/partitions', acknowledge and move on. There will future opportunities to solve worthy puzzles.

For linux software raid, '/proc/mdstat' and the 'mdadm' tool are your only true allys.

Cheers,

Last edited by lazardo; 05-07-2012 at 11:40 PM.
 
  


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