1 Topic by watsot2

  • watsot2
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Topic: GParted Error Message on Raid 1 Array

Hello,
    I've set up a Linux software raid 1 array using 2 WD hard drives.  Everything seems to be working fine; however, when I try to view the array in GParted, I get the following error messages for the individual devices and the array, respectively:

Unable to detect file system! Possible reasons are:
- The file system is damaged
- The file system is unknown to GParted
- There is no file system available (unformatted)
- The device entry /dev/sdb1 is missing

e2label: No such file or directory while trying to open /dev/md0p1
Couldn't find valid filesystem superblock.

tune2fs 1.42.9 (28-Dec-2013)

tune2fs: No such file or directory while trying to open /dev/md0p1
Couldn't find valid filesystem superblock.
Couldn't find valid filesystem superblock.

dumpe2fs 1.42.9 (28-Dec-2013)
dumpe2fs: No such file or directory while trying to open /dev/md0p1

Unable to read the contents of this file system!
Because of this some operations may be unavailable.
The cause might be a missing software package.
The following list of software packages is required for ext4 file system support:  e2fsprogs v1.41+.

I verified that I have a version of e2fsprogs installed that is greater than 1.41.  When I run sudo parted /dev/sdb print, sudo parted /dev/sdc print, and sudo parted /dev/md0 print, i get the following:

$ sudo parted /dev/sdb print
Model: ATA WDC WD10EZEX-60W (scsi)
Disk /dev/sdb: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Disk Flags:

Number  Start   End     Size    Type     File system  Flags
1      1049kB  1000GB  1000GB  primary               raid

sudo parted /dev/sdc print
Model: ATA WDC WD10EZEX-60W (scsi)
Disk /dev/sdc: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Disk Flags:

Number  Start   End     Size    Type     File system  Flags
1      1049kB  1000GB  1000GB  primary               raid

sudo parted /dev/md0 print
Model: Linux Software RAID Array (md)
Disk /dev/md0: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: loop
Disk Flags:

Number  Start  End     Size    File system  Flags
1      0.00B  1000GB  1000GB  ext4

So, it seems like I partitioned each drive with an msdos partition table, but didn't format them individually with an ext4 filesystem, but when I created the software raid, i assigned it an ext4 filesystem, but didn't generate a valid partition table. (???)

Is there anything I should have done differently, and/or is GParted telling me the full story, since a file system is assigned to the array?  Is there anything I can do that would otherwise be painless (read: not require a back up of my data) or would starting from scratch be the only option? Finally, if the setup is incorrect, would the correct set of steps have been: 1)create a partition on the entirety of each disk 2)set up a file system on each disk, 3)set up the raid array with mdadm as I appear to have already done?

2 Reply by gedakc

  • gedakc
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Re: GParted Error Message on Raid 1 Array

If a RAID is created using a collection of drives, then all partitioning and formatting operations should be performed on the RAID device path, and never the individual device paths.

RAID 1 is a mirror of the drive image, so it is understandable that some information can be seen when running a partitioning tool against a single drive within the RAID.

Based on the information provided it appears that /dev/md0 was formatted with the ext4 file system and no partition table was created [e.g., Partition Table = loop].

Again, after creating the RAID then only the RAID device path should be used in partition and format operations.

3 Reply by mfleetwo

  • mfleetwo
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Re: GParted Error Message on Raid 1 Array

@watsot2
What version of GParted are you running?  Is that from GParted Live CD, other live CD or your desktop?  What desktop?

For diagnostics what do the following commands report:

blkid
cat /proc/mdstat
sudo mdadm --examine --scan --verbose