Linux/mdadm/Notes

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mdadm notes

Notes

Copy partition table:

sfdisk -d /dev/sda | sfdisk /dev/sdb

Create md device:

mknod /dev/md<number> b <MAJOR> <MINOR>

References

Build a RAID 5 device

Check for existing md devices:

cat /proc/mdstat

Check if the not used md device exists

ls /dev/md1

If you need to create the device:

# look at existing md devices for MAJOR and MINOR values
file /dev/md*

# Create md device
# where 9 matches the already created
# and the 1 is the next increment up from the already created
mknod /dev/md1 b 9 1

Create 3 raid type partitions (type=fd):

/fdisk /dev/sda1
...
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

Create RAID 5 md device:

/sbin/mdadm --create --verbose /dev/<md_device_name> --level=5 --raid-devices=3 <partitions...>

/sbin/mdadm --create --verbose /dev/md1 --level=5 --raid-devices=3 \
   /dev/hdc1 /dev/hde1 /dev/hdg1
#or
/sbin/mdadm --create --verbose /dev/md1 --level=5 --raid-devices=3 \
   /dev/hd[ceg]1

Add device:

mdadm /dev/md0 --add /dev/sc1

Add spare: (spares are automatically selected when more than the capacity of disks is added)

mdadm /dev/md0 --add /dev/sc1

Wait for RAID to be rebuilt:

watch cat /proc/mdstat

Show MD details:

mdadm --detail <md_device_name>

mdadm --detail /dev/md1

BASIC:

Format with file system:

mkfs.ext3 /dev/md1

Mount new device:

mkdir /data
mount /dev/md1 /data

Make mount permanent:

vi /etc/fstab
#device		mount point	fs	options			fs_freq fs_passno
/dev/md1		/data		ext3	defaults,noatime	1 2

LVM:

Create Volume Group:

pvcreate /dev/md1
vgcreate lvm-raid /dev/md1

"The default value for the physical extent size can be too low for a large RAID array. In those cases you'll need to specify the -s option with a larger than default physical extent size. The default is only 4MB as of the version in Fedora Core 5. The maximum number of physical extents is approximately 65k so take your maximum volume size and divide it by 65k then round it to the next nice round number. For example, to successfully create a 550G RAID let's figure that's approximately 550,000 megabytes and divide by 65,000 which gives you roughly 8.46. Round it up to the next nice round number and use 16M (for 16 megabytes) as the physical extent size and you'll be fine:" [1]

vgcreate -s 16M <volume group name> <physical volume>

"Ok, you've created a blank receptacle but now you have to tell how many Physical Extents from the physical device (/dev/md0 in this case) will be allocated to this Volume Group. In my case I wanted all the data from /dev/md0 to be allocated to this Volume Group. If later I wanted to add additional space I would create a new RAID array and add that physical device to this Volume Group.

To find out how many PEs are available to me use the vgdisplay command to find out how many are available and now I can create a Logical Volume using all (or some) of the space in the Volume Group. In my case I call the Logical Volume lvm0." [2]

vgdisplay lvm-raid
 ...
 Free  PE / Size       57235 / 223.57 GB
lvcreate -l 57235 lvm-raid -n lvm0

This will create the following partition to use:

/dev/lvm-raid/lvm0

Format with file system:

mkfs.ext3 /dev/lvm-raid/lvm0

Mount new device:

mkdir /data
mount /dev/lvm-raid/lvm0 /data

Make mount permanent:

vi /etc/fstab
#device		mount point	fs	options			fs_freq fs_passno
/dev/lvm-raid/lvm0	/data		ext3	defaults,noatime	1 2

References:

Configuration File

Generally you do not need a configuration file for mdadm devices. During a rebuild it does come in handy though.

Configuration file:

/etc/mdadm.conf
# from man mdadm
# This will create a prototype config file that describes currently active arrays that are known to be made
# from partitions of IDE or SCSI drives.  This file should be reviewed before being used as it may  contain
# unwanted detail.
echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > mdadm.conf
mdadm --detail --scan >> mdadm.conf

Fix Broken RAID

mdadm --stop /dev/md3
mdadm --create /dev/md3 --verbose --level=raid5 --raid-devices=3  --spare-devices=0 /dev/hd[ceg]1
mdadm --detail /dev/md3
cat /proc/mdstat
mdadm /dev/md3 --fail /dev/hdc1 --remove /dev/hdc1
mdadm --stop /dev/md3
mdadm --assemble /dev/md3


Reassemble array manually:

# Find UUID with examine (--examine or -E):
mdadm --examine /dev/sda1
# Assemble (--assemble or -A) by UUID (--uuid or -u)
mdadm --assemble /dev/md1 --uuid [UUID]
# Combined
mdadm --assemble /dev/md1 --uuid $( mdadm --examine /dev/sda1 | grep UUID | awk '{print $3}' )

See also Linux Recovery

References

TODO

  • Will LVM survive reboot?
  • Will MD survive reboot?
  • Will LVM survive reinstall of OS?
  • Will md device survive reinstall of OS? Create a pure MD device and LVM device, and test on OS reinstall.

RAID 5 Setup

Using this as a reference.

Another good tutorial: Root-on-LVM-on-RAID HOWTO

[root@fileserver ~]# fdisk /dev/hdc

The number of cylinders for this disk is set to 30401.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/hdc: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-30401, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-30401, default 30401):
Using default value 30401

Command (m for help): p

Disk /dev/hdc: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdc1               1       30401   244196001   83  Linux

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

Command (m for help): p

Disk /dev/hdc: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdc1               1       30401   244196001   fd  Linux raid autodetect

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

Repeated for /dev/hde and /dev/hdg...

[root@fileserver ~]# fdisk -l

Disk /dev/hda: 61.4 GB, 61492838400 bytes
255 heads, 63 sectors/track, 7476 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1          13      104391   83  Linux
/dev/hda2              14        7476    59946547+  8e  Linux LVM

Disk /dev/hdc: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdc1               1       30401   244196001   fd  Linux raid autodetect

Disk /dev/hde: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hde1               1       30401   244196001   fd  Linux raid autodetect

Disk /dev/hdg: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdg1               1       30401   244196001   fd  Linux raid autodetect

Disk /dev/dm-0: 59.2 GB, 59257126912 bytes
255 heads, 63 sectors/track, 7204 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/dm-0 doesn't contain a valid partition table

Disk /dev/dm-1: 2080 MB, 2080374784 bytes
255 heads, 63 sectors/track, 252 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/dm-1 doesn't contain a valid partition table

Create RAID 5 array

[root@fileserver ~]# /sbin/mdadm --create --verbose /dev/md2 --level=5 --raid-devices=3 \
    /dev/hdc1 /dev/hde1 /dev/hdg1
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 64K
mdadm: /dev/hdc1 appears to contain an ext2fs file system
    size=104388K  mtime=Sat Nov 18 05:47:04 2006
mdadm: size set to 244195904K
Continue creating array? y
mdadm: array /dev/md2 started.

Examine the array

[root@fileserver ~]# mdadm --detail /dev/md2
/dev/md2:
        Version : 00.90.03
  Creation Time : Thu Nov 23 23:24:27 2006
     Raid Level : raid5
     Array Size : 488391808 (465.77 GiB 500.11 GB)
    Device Size : 244195904 (232.88 GiB 250.06 GB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 2
    Persistence : Superblock is persistent

    Update Time : Thu Nov 23 23:24:27 2006
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : e5748042:19bf53d2:3d646fcb:1293ea5d
         Events : 0.1

    Number   Major   Minor   RaidDevice State
       0      22        1        0      active sync   /dev/hdc1
       1      33        1        1      active sync   /dev/hde1
       0       0        0    9923072      removed

       3      34        1        3      active sync   /dev/hdg1

Curious what this line indicates...

        0       0        0    9923072      removed

Following Initial set of LVM on top of RAID.

RAID 5 Performance

/dev/hdc1 and /dev/hde1 and /dev/hdg1 in RAID 5 configuration

[root@fileserver ~]# hdparm -Tt /dev/lvm-raid/lvm0
/dev/lvm-raid/lvm0:
#1
 Timing cached reads:   3332 MB in  2.00 seconds = 1665.86 MB/sec
 Timing buffered disk reads:  380 MB in  3.01 seconds = 126.18 MB/sec
#2
 Timing cached reads:   3328 MB in  2.00 seconds = 1662.68 MB/sec
 Timing buffered disk reads:  378 MB in  3.00 seconds = 125.98 MB/sec
#3
 Timing cached reads:   3356 MB in  2.00 seconds = 1677.87 MB/sec
 Timing buffered disk reads:  380 MB in  3.01 seconds = 126.32 MB/sec
#4
 Timing cached reads:   3348 MB in  2.00 seconds = 1674.49 MB/sec
 Timing buffered disk reads:  380 MB in  3.01 seconds = 126.18 MB/sec

It appears that the RAID 5 has the same performance as the 2 disk stripped test.

Raid build failure

[root@hal ~]# mdadm --create --verbose /dev/md2 --level=raid0 --raid-devices=3 /dev/hd[dfh]1
mdadm: error opening /dev/md2: No such file or directory

error opening /dev/md2: No such file or directory
http://www.issociate.de/board/post/145249/error_opening_/dev/md2:_No_such_file_or_directory.html

mknod /dev/md2 b 9 2

[root@hal ~]# file /dev/md*
/dev/md0: block special (9/0)
/dev/md1: block special (9/1)

[root@hal ~]# file /dev/md*
/dev/md0: block special (9/0)
/dev/md1: block special (9/1)
/dev/md2: block special (9/2)

[root@hal ~]# mdadm --create --verbose /dev/md2 --level=raid0 --raid-devices=3 /dev/hd[dfh]1
mdadm: chunk size defaults to 64K
mdadm: array /dev/md2 started.

[root@hal ~]# mkfs.ext3 /dev/md2
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
73269248 inodes, 146518752 blocks
7325937 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
4472 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
        102400000

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

Broken RAID 5?

[root@fileserver ~]# mdadm --stop /dev/md3
[root@fileserver ~]# mdadm --create /dev/md3 --verbose --level=raid5 --raid-devices=3  --spare-devices=0 /dev/hd[ceg]1
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 64K
mdadm: /dev/hdc1 appears to contain an ext2fs file system
    size=240974720K  mtime=Wed Dec 31 17:00:00 1969
mdadm: /dev/hdc1 appears to be part of a raid array:
    level=raid5 devices=3 ctime=Fri Nov 24 12:27:47 2006
mdadm: /dev/hde1 appears to be part of a raid array:
    level=raid5 devices=3 ctime=Fri Nov 24 12:27:47 2006
mdadm: /dev/hdg1 appears to contain an ext2fs file system
    size=240974720K  mtime=Wed Dec 31 17:00:00 1969
mdadm: /dev/hdg1 appears to be part of a raid array:
    level=raid5 devices=3 ctime=Fri Nov 24 12:27:47 2006
mdadm: size set to 120487360K
Continue creating array? y
mdadm: array /dev/md3 started.
[root@fileserver ~]# mdadm --detail /dev/md3
/dev/md3:
        Version : 00.90.03
  Creation Time : Fri Nov 24 12:38:19 2006
     Raid Level : raid5
     Array Size : 240974720 (229.81 GiB 246.76 GB)
    Device Size : 120487360 (114.91 GiB 123.38 GB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 3
    Persistence : Superblock is persistent

    Update Time : Fri Nov 24 12:38:19 2006
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 70b25481:ebbf8e5b:c8c3a366:13d2ddcd
         Events : 0.1

    Number   Major   Minor   RaidDevice State
       0      22        1        0      active sync   /dev/hdc1
       1      33        1        1      active sync   /dev/hde1
       0       0        0        0      removed

       3      34        1        3      active sync   /dev/hdg1
[root@fileserver ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md3 : active raid5 hdg1[3] hde1[1] hdc1[0]
      240974720 blocks level 5, 64k chunk, algorithm 2 [3/2] [UU_]

md4 : active raid5 hdg2[3] hde2[1] hdc2[0]
      247416832 blocks level 5, 64k chunk, algorithm 2 [3/2] [UU_]

unused devices: <none>
[root@fileserver ~]# mdadm /dev/md3 --fail /dev/hdc1 --remove /dev/hdc1
mdadm: set /dev/hdc1 faulty in /dev/md3
mdadm: hot removed /dev/hdc1
[root@fileserver ~]# mdadm --stop /dev/md3
[root@fileserver ~]# mdadm --assemble /dev/md3
mdadm: device 3 in /dev/md3 has wrong state in superblock, but /dev/hdg1 seems ok
mdadm: /dev/md3 assembled from 1 drive and 1 spare - not enough to start the array.

It appears that other people have had similar issues:

  1. http://www.linuxquestions.org/questions/showthread.php?t=434067
  2. http://www.linuxquestions.org/questions/showthread.php?t=491325

Fixed RAID 5

After discussing with Clint the problem, we came to the conclusion that when the array was created, the system did not process the spare to convert it into the array. We assumed there was a bug with the raid5 module or the kernel. I rebuilt the system using Fedora Core 5 64bit edition, and upon creating the array, the spare was processed correctly. I was also pleased to see that the RAID 5 (even being broken), and the RAID 0 with LVM survied the reinstall of the OS.

Every 2.0s: cat /proc/mdstat                                                                         Fri Nov 24  19:04:03 2006

Personalities : [raid0] [raid6] [raid5] [raid4]
md3 : active raid5 hdg1[3] hde1[1] hdc1[0]
      240974720 blocks level 5, 64k chunk, algorithm 2 [3/2] [UU_]
      [>....................]  recovery =  0.8% (969652/120487360) finish=43.1min speed=46173K/sec

md4 : active raid0 hdg2[2] hde2[1] hdc2[0]
      371125248 blocks 64k chunks

unused devices: <none>

Creating md device

[root@hal ~]# mdadm --create --verbose /dev/md2 --level=raid0 --raid-devices=3 /dev/hd[dfh]1
mdadm: error opening /dev/md2: No such file or directory

error opening /dev/md2: No such file or directory
http://www.issociate.de/board/post/145249/error_opening_/dev/md2:_No_such_file_or_directory.html

[root@hal ~]# file /dev/md*
/dev/md0: block special (9/0)
/dev/md1: block special (9/1)

# where the 9 matches the others
# and the 2 is the next increment above the exisiting
mknod /dev/md2 b 9 2

[root@hal ~]# file /dev/md*
/dev/md0: block special (9/0)
/dev/md1: block special (9/1)
/dev/md2: block special (9/2)

[root@hal ~]# mdadm --create --verbose /dev/md2 --level=raid0 --raid-devices=3 /dev/hd[dfh]1
mdadm: chunk size defaults to 64K
mdadm: array /dev/md2 started.

[root@hal ~]# mkfs.ext3 /dev/md2
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
73269248 inodes, 146518752 blocks
7325937 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
4472 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
        102400000

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

Chunk Size

5.10 Chunk sizes

The chunk-size deserves an explanation. You can never write completely parallel to a set of disks. If you had two disks and wanted to write a byte, you would have to write four bits on each disk, actually, every second bit would go to disk 0 and the others to disk 1. Hardware just doesn't support that. Instead, we choose some chunk-size, which we define as the smallest "atomic" mass of data that can be written to the devices. A write of 16 kB with a chunk size of 4 kB, will cause the first and the third 4 kB chunks to be written to the first disk, and the second and fourth chunks to be written to the second disk, in the RAID-0 case with two disks. Thus, for large writes, you may see lower overhead by having fairly large chunks, whereas arrays that are primarily holding small files may benefit more from a smaller chunk size.

Chunk sizes must be specified for all RAID levels, including linear mode. However, the chunk-size does not make any difference for linear mode.

For optimal performance, you should experiment with the value, as well as with the block-size of the filesystem you put on the array.

The argument to the chunk-size option in /etc/raidtab specifies the chunk-size in kilobytes. So "4" means "4 kB".


"A reasonable chunk-size for RAID-5 is 128 kB, but as always, you may want to experiment with this." [3]

To Read

Virtual Play

My posting to PLUG 2009.07.08:

Mike,

By the way, if you are wanting to play around with mdadm without actually using real drives you 
can setup a few virtual devices and play with mdadm to your hearts content without destroying real disks:

dd if=/dev/zero of=/root/vd1 bs=1M count=100   # create virtual disk 1
dd if=/dev/zero of=/root/vd2 bs=1M count=100   # create virtual disk 2
dd if=/dev/zero of=/root/vd3 bs=1M count=100   # create virtual disk 3
dd if=/dev/zero of=/root/vd4 bs=1M count=100   # create virtual disk 4

losetup -a  # show currently used loop devices

losetup /dev/loop1 /root/vd1  # use an unused loop device
losetup /dev/loop2 /root/vd2  # use an unused loop device
losetup /dev/loop3 /root/vd3  # use an unused loop device
losetup /dev/loop4 /root/vd4  # use an unused loop device

mdadm --create /dev/md2 --level raid10 --raid-devices 4 /dev/loop[1234]  # create md devices (use unused /dev/md?)
mkfs.ext3 /dev/md2  # format as ext3
mount /dev/md2 /mnt/md2  # mount if you want

now you can fail virtual disks, stop array, reassemble, fail disks, etc to your hearts content.

# example rebuild with one less disk:
mdadm --stop /dev/md2
mdadm --assemble /dev/md2 /dev/loop[123]

When you are done, to clean up:

umount /dev/md2   # if mounted
mdadm --stop /dev/md2
losetup -d /dev/loop1
losetup -d /dev/loop2
losetup -d /dev/loop3
losetup -d /dev/loop4
rm /root/vd1
rm /root/vd2
rm /root/vd3
rm /root/vd4

Odd Failure on Rebuild

Aug 18 19:17:53 prime kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Aug 18 19:17:53 prime kernel: ata1.00: irq_stat 0x40000001
Aug 18 19:17:53 prime kernel: ata1.00: failed command: READ DMA EXT
Aug 18 19:17:53 prime kernel: ata1.00: cmd 25/00:38:b3:01:43/00:03:75:00:00/e0 tag 4 dma 421888 in
Aug 18 19:17:53 prime kernel:         res 51/40:00:ba:04:43/00:00:75:00:00/00 Emask 0x9 (media error)
Aug 18 19:17:53 prime kernel: ata1.00: status: { DRDY ERR }
Aug 18 19:17:53 prime kernel: ata1.00: error: { UNC }
Aug 18 19:17:53 prime kernel: ata1.00: configured for UDMA/133
Aug 18 19:17:53 prime kernel: ata1: EH complete
Aug 18 19:17:56 prime kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Aug 18 19:17:56 prime kernel: ata1.00: irq_stat 0x40000001
Aug 18 19:17:56 prime kernel: ata1.00: failed command: READ DMA EXT
Aug 18 19:17:56 prime kernel: ata1.00: cmd 25/00:38:b3:01:43/00:03:75:00:00/e0 tag 5 dma 421888 in
Aug 18 19:17:56 prime kernel:         res 51/40:00:ba:04:43/00:00:75:00:00/00 Emask 0x9 (media error)
Aug 18 19:17:56 prime kernel: ata1.00: status: { DRDY ERR }
Aug 18 19:17:56 prime kernel: ata1.00: error: { UNC }
Aug 18 19:17:56 prime kernel: ata1.00: configured for UDMA/133
Aug 18 19:17:56 prime kernel: ata1: EH complete
Aug 18 19:17:59 prime kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Aug 18 19:17:59 prime kernel: ata1.00: irq_stat 0x40000001
Aug 18 19:17:59 prime kernel: ata1.00: failed command: READ DMA EXT
Aug 18 19:17:59 prime kernel: ata1.00: cmd 25/00:38:b3:01:43/00:03:75:00:00/e0 tag 6 dma 421888 in
Aug 18 19:17:59 prime kernel:         res 51/40:00:ba:04:43/00:00:75:00:00/00 Emask 0x9 (media error)
Aug 18 19:17:59 prime kernel: ata1.00: status: { DRDY ERR }
Aug 18 19:17:59 prime kernel: ata1.00: error: { UNC }
Aug 18 19:17:59 prime kernel: ata1.00: configured for UDMA/133
Aug 18 19:17:59 prime kernel: ata1: EH complete
Aug 18 19:18:01 prime kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Aug 18 19:18:01 prime kernel: ata1.00: irq_stat 0x40000001
Aug 18 19:18:01 prime kernel: ata1.00: failed command: READ DMA EXT
Aug 18 19:18:01 prime kernel: ata1.00: cmd 25/00:38:b3:01:43/00:03:75:00:00/e0 tag 7 dma 421888 in
Aug 18 19:18:01 prime kernel:         res 51/40:00:ba:04:43/00:00:75:00:00/00 Emask 0x9 (media error)
Aug 18 19:18:01 prime kernel: ata1.00: status: { DRDY ERR }
Aug 18 19:18:01 prime kernel: ata1.00: error: { UNC }
Aug 18 19:18:02 prime kernel: ata1.00: configured for UDMA/133
Aug 18 19:18:02 prime kernel: ata1: EH complete
Aug 18 19:18:04 prime kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Aug 18 19:18:04 prime kernel: ata1.00: irq_stat 0x40000001
Aug 18 19:18:04 prime kernel: ata1.00: failed command: READ DMA EXT
Aug 18 19:18:04 prime kernel: ata1.00: cmd 25/00:38:b3:01:43/00:03:75:00:00/e0 tag 8 dma 421888 in
Aug 18 19:18:04 prime kernel:         res 51/40:00:ba:04:43/00:00:75:00:00/00 Emask 0x9 (media error)
Aug 18 19:18:04 prime kernel: ata1.00: status: { DRDY ERR }
Aug 18 19:18:04 prime kernel: ata1.00: error: { UNC }
Aug 18 19:18:04 prime kernel: ata1.00: configured for UDMA/133
Aug 18 19:18:04 prime kernel: ata1: EH complete
Aug 18 19:18:07 prime kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Aug 18 19:18:07 prime kernel: ata1.00: irq_stat 0x40000001
Aug 18 19:18:07 prime kernel: ata1.00: failed command: READ DMA EXT
Aug 18 19:18:07 prime kernel: ata1.00: cmd 25/00:38:b3:01:43/00:03:75:00:00/e0 tag 9 dma 421888 in
Aug 18 19:18:07 prime kernel:         res 51/40:00:ba:04:43/00:00:75:00:00/00 Emask 0x9 (media error)
Aug 18 19:18:07 prime kernel: ata1.00: status: { DRDY ERR }
Aug 18 19:18:07 prime kernel: ata1.00: error: { UNC }
Aug 18 19:18:07 prime kernel: ata1.00: configured for UDMA/133
Aug 18 19:18:07 prime kernel: sd 0:0:0:0: [sda] Unhandled sense code
Aug 18 19:18:07 prime kernel: sd 0:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Aug 18 19:18:07 prime kernel: sd 0:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor]
Aug 18 19:18:07 prime kernel: Descriptor sense data with sense descriptors (in hex):
Aug 18 19:18:07 prime kernel:        72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
Aug 18 19:18:07 prime kernel:        75 43 04 ba
Aug 18 19:18:07 prime kernel: sd 0:0:0:0: [sda] Add. Sense: Unrecovered read error - auto reallocate failed
Aug 18 19:18:07 prime kernel: sd 0:0:0:0: [sda] CDB: Read(10): 28 00 75 43 01 b3 00 03 38 00
Aug 18 19:18:07 prime kernel: md/raid:md4: Disk failure on sda3, disabling device.
Aug 18 19:18:07 prime kernel: md/raid:md4: Operation continuing on 4 devices.
Aug 18 19:18:07 prime kernel: ata1: EH complete
Aug 18 19:18:07 prime kernel: md: md4: recovery done.