raid trouble?

lundi 22 août 2016

Just a "quick" couple of questions about a raid1 setup on a clean desktop install of xubuntu 16.04.

A. Background

Disks /dev/sdb and /dev/sdc were part of a RAID + LVM configuration in the immediately previous (12.04) install.

The current raid1 array is being used for data only.

The current system resides on a separate disk /dev/sda and is not part of this raid configuration.

I created the raid array and added the ext4 file system to /dev/md0:

Code:

sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb /dev/sdc
sudo mkfs.ext4 /dev/md0

I created a mount point and added an entry to fstab:

Code:

# /dev/md0
UUID=x-x-x-x-x /home/server/shared ext4 defaults 0 0

I scanned array details into the mdadm.conf file:

Code:

sudo mdadm --detail --scan /dev/md0 >> /etc/mdadm/mdadm.conf

A mdadm --detail /dev/md0 shows:

Code:

/dev/md0:
        Version : 1.2
  Creation Time : Sun Aug 21 17:50:26 2016
     Raid Level : raid1
     Array Size : 976631488 (931.39 GiB 1000.07 GB)
  Used Dev Size : 976631488 (931.39 GiB 1000.07 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Mon Aug 22 09:38:30 2016
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : server:0  (local to host server)
           UUID : a:a:a:a
         Events : 2576

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc

A mdadm --examine of /dev/sdb shows:

Code:

/dev/sdb:
          Magic : same as sdc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : a:a:a:a
           Name : server:0  (local to host server)
  Creation Time : Sun Aug 21 17:50:26 2016
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 1953263024 (931.39 GiB 1000.07 GB)
     Array Size : 976631488 (931.39 GiB 1000.07 GB)
  Used Dev Size : 1953262976 (931.39 GiB 1000.07 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=48 sectors
          State : clean
    Device UUID : b:b:b:b

Internal Bitmap : 8 sectors from superblock
    Update Time : Mon Aug 22 09:38:30 2016
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : b - correct
         Events : 2576


   Device Role : Active device 0
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)

A mdadm --examine /dev/sdc shows:

Code:

/dev/sdc:
          Magic : same as sdb
        Version : 1.2
    Feature Map : 0x1
     Array UUID : a:a:a:a
           Name : server:0  (local to host server)
  Creation Time : Sun Aug 21 17:50:26 2016
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 1953263024 (931.39 GiB 1000.07 GB)
     Array Size : 976631488 (931.39 GiB 1000.07 GB)
  Used Dev Size : 1953262976 (931.39 GiB 1000.07 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=48 sectors
          State : clean
    Device UUID : c:c:c:c

Internal Bitmap : 8 sectors from superblock
    Update Time : Mon Aug 22 09:38:30 2016
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : c - correct
         Events : 2576


   Device Role : Active device 1
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)

B. Questions

1. In performing fsck.ext4 on devices /dev/sdb and /dev/sdc, I receive the following identical output, for both (sdb is shown). A "bad block" reference appears, again (as it did in --examine). Are these bad signs? Should this be reparable?

Code:

e2fsck 1.42.13 (17-May-2015)
ext2fs_open2: Bad magic number in super-block
fsck.ext4: Superblock invalid, trying backup blocks...
fsck.ext4: Bad magic number in super-block while trying to open /dev/sdb

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>
 or
    e2fsck -b 32768 <device>

2. A "mounted" icon representing the raid array (dev/md0) appears on my desktop. The array is also mounted at the fstab-described mount point. When I click on the desktop icon, it seems to open to the raid array. When I umount /dev/md0 - BOTH the desktop icon and fstab-reference to the raid array are unmounted. Can I remove the desktop icon? Does the raid array's presence on the Desktop as well at its fstab mount point represent a problem?