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So I have been posting a lot about a RAID build with MDADM and Ubuntu (sorry about that). Im just not understanding whats going on with my setup.

I have a RAID-5 setup, and followed this guide exactly to do so: http://zackreed.me/articles/38-software-raid-5-in-debian-with-mdadm

Anwyay, Im running into this consistent problem. I turn off the RAID at times when I dont need it up, and when I turn it back on I get stuck at a purple screen. I can get out of this screen by simply typing in exit, and it will tell me my raid is Degraded, asking if I wish to boot it or not. After that, its the normal login screen. Then, this is what I see via SSH: (typing it out)

mdadm-D /dev/md127

Then it returns to me that one of the drives is "removed"

Then I will: 

mdadm --manage /dev/md127 --add /dev/sd** (** standing for the drive)

This is what I always get back

mdadm: /dev/sd** reports being an active member for /dev/md127, but a --re-add fails.
mdadm: not performing --add as that would convert /dev/sdb1 in to a spare.
mdadm: To make this a spare, use "mdadm --zero-superblock /dev/sd**" first.

So, I will follow those instructions and then once again re-add the drive, and then the RAID will rebuild fine.

What I am frustrated with is this happens so often, and I have no idea why. Can anyone help me out? Sometimes it works fine, and sometimes it doesn't. All that I am doing is turning it off, or on. Any help is greatly appreciated, I dont understand why my RAID wont just work normally or what I am doing wrong.

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18
  • What do you mean by "turning it off"?
    – StarNamer
    Jul 31, 2012 at 19:44
  • I mean shutting down the computer
    – vpoola88
    Jul 31, 2012 at 20:03
  • 1
    After you've rebooted and found you needed to rebuild the array, you should check /var/log/syslog or possibly /var/log/syslog.1 and see what messages there were prior to the last shutdown/restart. You should be able to just do sudo less /var/log/syslog and then search for 6 zeros (/000000). This will find the startup messages and you can just move backwards (PgUp) for the shutdown messages.
    – StarNamer
    Aug 1, 2012 at 22:45
  • 1
    Searching for 000000 is just a quick way to find the startup messages in /var/log/syslog. If you then look at the lines preceeding the startup, you will see the messages from the last shutdown where you might find an error messages about the disks.
    – StarNamer
    Aug 6, 2012 at 22:17
  • 1
    Depending on the drive type you can look at the SMART info using sudo smartctl -i /dev/sdb (may need sudo apt-get install smartmontools). smartctl -H /dev/sdb will report overall health of the drive; smartctl -a /dev/sdb will report errors (plus the above 2). If smartctl doesn't report the drive (e.g. some USB) you need to use something else (or look at the startup log in /var/log/syslog).
    – StarNamer
    Aug 7, 2012 at 10:47

1 Answer 1

Reset to default
2

I just had a similar problem when I rebooted my home file server and came looking for a similar error.

When using "smartctl --all /dev/sda" (for example) it's useful to check the value of Reallocated_Sector_Ct, if this is non zero and starts climbing dramatically then it means your disk could be failing and it's time to take a backup.

here's the values from my pair of drives (be sure to scroll to the right to see the field values)

sda:

ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x002f   200   200   051    Pre-fail  Always       -       0
  3 Spin_Up_Time            0x0027   162   161   021    Pre-fail  Always       -       6875
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       50
  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x002e   200   200   000    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   065   065   000    Old_age   Always       -       25675
 10 Spin_Retry_Count        0x0032   100   253   000    Old_age   Always       -       0
 11 Calibration_Retry_Count 0x0032   100   253   000    Old_age   Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       48
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       9
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       50
194 Temperature_Celsius     0x0022   105   099   000    Old_age   Always       -       45
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   200   200   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       5
200 Multi_Zone_Error_Rate   0x0008   200   200   000    Old_age   Offline      -       0

and sdb:

ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x002f   200   200   051    Pre-fail  Always       -       0
  3 Spin_Up_Time            0x0027   164   164   021    Pre-fail  Always       -       6775
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       38
  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x002e   200   200   000    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   066   066   000    Old_age   Always       -       25548
 10 Spin_Retry_Count        0x0032   100   253   000    Old_age   Always       -       0
 11 Calibration_Retry_Count 0x0032   100   253   000    Old_age   Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       36
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       6
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       38
194 Temperature_Celsius     0x0022   110   099   000    Old_age   Always       -       40
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   200   200   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0008   200   200   000    Old_age   Offline      -       0

the good news is that I'm getting raw value 0 for the reallocated sector counts.

hope this helps

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3
  • so, happened again, and it is the same drive. I have a spare drive that I wanna swap to see if that problem continue to exist. How do i find out which drive is specifically /sdb?
    – vpoola88
    Aug 16, 2012 at 21:08
  • Hey all, I was wondering if I unplug all my drives, and replugged them in a different order, if that would mess up my array? Or is that irrelevant?
    – vpoola88
    Sep 6, 2012 at 21:26
  • mdraid will work out where the devices are if you put them on a different sata bus. If you're not using mdraid, be sure your fstab refers to drives by label or uuid, not by the underlying device name.. i.e. don't use /dev/sda1 for example.
    – Paul M
    Apr 17, 2015 at 10:52

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