Syncing went through. And here we are:
[root@real-saturn ~]# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sdb2[0] sda2[1]
      488279488 blocks [2/2] [UU]
md1 : active raid1 sdb1[0] sda1[1]
      104320 blocks [2/2] [UU]
unused devices: <none>
and:
This email was generated by the smartd daemon running on:
   host name: real-saturn
  DNS domain: real.ivb.org
  NIS domain: (none)
The following warning/error was logged by the smartd daemon:
Device: /dev/sda, ATA error count increased from 3814 to 3815
For details see host's SYSLOG (default: /var/log/messages).
You can also use the smartctl utility for further investigation.
Another email message will be sent in 1 days if the problem persists
and:
[root@real-saturn ~]# fdisk -lu /dev/sda; fdisk -lu /dev/sdb
Platte /dev/sda: 500.1 GByte, 500107862016 Byte
255 Köpfe, 63 Sektoren/Spuren, 60801 Zylinder, total 976773168 sectors
Einheiten = Sektoren von 1 * 512 = 512 Bytes
    Gerät Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1      208769      104384+  fd  Linux raid autodetect
Partition 1 endet nicht an einer Zylindergrenze.
/dev/sda2          208770   976768063   488279647   fd  Linux raid autodetect
Platte /dev/sdb: 500.1 GByte, 500107862016 Byte
255 Köpfe, 63 Sektoren/Spuren, 60801 Zylinder, total 976773168 sectors
Einheiten = Sektoren von 1 * 512 = 512 Bytes
    Gerät Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1      208769      104384+  fd  Linux raid autodetect
Partition 1 endet nicht an einer Zylindergrenze.
/dev/sdb2          208770   976768063   488279647   fd  Linux raid autodetect
and:
[root@real-saturn ~]# smartctl -a /dev/sda
smartctl version 5.33 [i686-redhat-linux-gnu] Copyright (C) 2002-4 Bruce Allen
Home page is 
http://smartmontools.sourceforge.net/=== START OF INFORMATION SECTION ===
Device Model:     ST3500630AS
Serial Number:    6QG3A7B0
Firmware Version: 3.AAK
User Capacity:    500,107,862,016 bytes
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   7
ATA Standard is:  Exact ATA specification draft version not indicated
Local Time is:    Fri Nov 19 22:46:50 2010 CET
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status:  (0x82) Offline data collection activity
                                        was completed without error.
                                        Auto Offline Data Collection: Enabled.
Self-test execution status:      (  24) The self-test routine was aborted by
                                        the host.
Total time to complete Offline
data collection:                 ( 430) seconds.
Offline data collection
capabilities:                    (0x5b) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        command.
                                        Offline surface scan supported.
                                        Self-test supported.
                                        No Conveyance Self-test supported.
                                        Selective Self-test supported.
SMART capabilities:            (0x0003) Saves SMART data before entering
                                        power-saving mode.
                                        Supports SMART auto save timer.
Error logging capability:        (0x01) Error logging supported.
                                        General Purpose Logging supported.
Short self-test routine
recommended polling time:        (   1) minutes.
Extended self-test routine
recommended polling time:        ( 163) minutes.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000f   115   100   006    Pre-fail  Always       -       90420120
  3 Spin_Up_Time            0x0003   093   093   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       86
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000f   082   060   030    Pre-fail  Always       -       185476578
  9 Power_On_Hours          0x0032   078   078   000    Old_age   Always       -       19876
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       86
187 Unknown_Attribute       0x0032   001   001   000    Old_age   Always       -       3488
189 Unknown_Attribute       0x003a   100   100   000    Old_age   Always       -       0
190 Unknown_Attribute       0x0022   062   055   045    Old_age   Always       -       707133478
194 Temperature_Celsius     0x0022   038   045   000    Old_age   Always       -       38 (Lifetime Min/Max 0/24)
195 Hardware_ECC_Recovered  0x001a   068   057   000    Old_age   Always       -       107020588
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x003e   200   200   000    Old_age   Always       -       1
200 Multi_Zone_Error_Rate   0x0000   100   253   000    Old_age   Offline      -       0
202 TA_Increase_Count       0x0032   100   253   000    Old_age   Always       -       0
SMART Error Log Version: 1
ATA Error Count: 3815 (device log contains only the most recent five errors)
        CR = Command Register [HEX]
        FR = Features Register [HEX]
        SC = Sector Count Register [HEX]
        SN = Sector Number Register [HEX]
        CL = Cylinder Low Register [HEX]
        CH = Cylinder High Register [HEX]
        DH = Device/Head Register [HEX]
        DC = Device Command Register [HEX]
        ER = Error register [HEX]
        ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.
Error 3815 occurred at disk power-on lifetime: 19875 hours (828 days + 3 hours)
  When the command that caused the error occurred, the device was active or idle.
  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 af 53 bb 0c e0  Error: ICRC, ABRT 175 sectors at LBA = 0x000cbb53 = 834387
  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  25 00 00 02 b8 0c e0 00      01:31:58.989  READ DMA EXT
  25 00 00 02 b4 0c e0 00      01:31:58.980  READ DMA EXT
  25 00 00 02 b0 0c e0 00      01:31:58.972  READ DMA EXT
  25 00 80 82 ac 0c e0 00      01:31:58.963  READ DMA EXT
  25 00 00 82 a8 0c e0 00      01:31:59.076  READ DMA EXT
Error 3814 occurred at disk power-on lifetime: 19872 hours (828 days + 0 hours)
  When the command that caused the error occurred, the device was active or idle.
  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 01 98 b9 94 e0  Error: UNC at LBA = 0x0094b998 = 9746840
  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  42 00 00 00 b8 94 e0 00      00:14:33.231  READ VERIFY SECTOR(S) EXT
  42 00 00 00 b0 94 e0 00      00:14:33.220  READ VERIFY SECTOR(S) EXT
  42 00 00 00 a8 94 e0 00      00:14:33.203  READ VERIFY SECTOR(S) EXT
  42 00 00 00 a0 94 e0 00      00:14:33.191  READ VERIFY SECTOR(S) EXT
  42 00 00 00 98 94 e0 00      00:14:33.174  READ VERIFY SECTOR(S) EXT
Error 3813 occurred at disk power-on lifetime: 19867 hours (827 days + 19 hours)
  When the command that caused the error occurred, the device was active or idle.
  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 98 b9 94 e7  Error: UNC at LBA = 0x0794b998 = 127187352
  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 70 92 b9 94 e7 00      01:30:05.464  READ DMA
  ec 03 46 00 00 00 a0 00      01:30:05.461  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      01:30:05.461  SET FEATURES [Set transfer mode]
  ec 00 00 98 b9 94 a0 00      01:30:05.459  IDENTIFY DEVICE
  c8 00 78 8a b9 94 e7 00      01:30:03.419  READ DMA
Error 3812 occurred at disk power-on lifetime: 19867 hours (827 days + 19 hours)
  When the command that caused the error occurred, the device was active or idle.
  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 98 b9 94 e7  Error: UNC at LBA = 0x0794b998 = 127187352
  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 78 8a b9 94 e7 00      01:30:05.464  READ DMA
  ec 03 46 00 00 00 a0 00      01:30:05.461  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      01:30:05.461  SET FEATURES [Set transfer mode]
  ec 00 00 98 b9 94 a0 00      01:30:05.459  IDENTIFY DEVICE
  c8 00 80 82 b9 94 e7 00      01:30:03.419  READ DMA
Error 3811 occurred at disk power-on lifetime: 19867 hours (827 days + 19 hours)
  When the command that caused the error occurred, the device was active or idle.
  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 98 b9 94 e7  Error: UNC at LBA = 0x0794b998 = 127187352
  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 80 82 b9 94 e7 00      01:29:59.327  READ DMA
  ec 03 46 00 00 00 a0 00      01:29:57.288  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      01:29:57.285  SET FEATURES [Set transfer mode]
  ec 00 00 98 b9 94 a0 00      01:29:57.285  IDENTIFY DEVICE
  c8 00 88 7a b9 94 e7 00      01:30:03.419  READ DMA
SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Aborted by host               80%     19873         -
# 2  Short offline       Completed without error       00%     19873         -
# 3  Short offline       Aborted by host               90%     19873         -
# 4  Short offline       Completed: read failure       90%     19873         127187352
# 5  Short offline       Completed: read failure       90%     19871         127187352
# 6  Short offline       Interrupted (host reset)      90%     19846         -
# 7  Short offline       Aborted by host               80%     19873         -
SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
and:
[root@real-saturn ~]# smartctl -a /dev/sdb
smartctl version 5.33 [i686-redhat-linux-gnu] Copyright (C) 2002-4 Bruce Allen
Home page is 
http://smartmontools.sourceforge.net/=== START OF INFORMATION SECTION ===
Device Model:     ST3500630AS
Serial Number:    9QG8S58F
Firmware Version: 3.AAK
User Capacity:    500,107,862,016 bytes
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   7
ATA Standard is:  Exact ATA specification draft version not indicated
Local Time is:    Fri Nov 19 22:48:56 2010 CET
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status:  (0x82) Offline data collection activity
                                        was completed without error.
                                        Auto Offline Data Collection: Enabled.
Self-test execution status:      (   0) The previous self-test routine completed
                                        without error or no self-test has ever
                                        been run.
Total time to complete Offline
data collection:                 ( 430) seconds.
Offline data collection
capabilities:                    (0x5b) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        command.
                                        Offline surface scan supported.
                                        Self-test supported.
                                        No Conveyance Self-test supported.
                                        Selective Self-test supported.
SMART capabilities:            (0x0003) Saves SMART data before entering
                                        power-saving mode.
                                        Supports SMART auto save timer.
Error logging capability:        (0x01) Error logging supported.
                                        General Purpose Logging supported.
Short self-test routine
recommended polling time:        (   1) minutes.
Extended self-test routine
recommended polling time:        ( 163) minutes.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000f   113   094   006    Pre-fail  Always       -       57276716
  3 Spin_Up_Time            0x0003   093   093   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       90
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always       -       14
  7 Seek_Error_Rate         0x000f   082   060   030    Pre-fail  Always       -       181467908
  9 Power_On_Hours          0x0032   078   078   000    Old_age   Always       -       19901
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       90
187 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       0
189 Unknown_Attribute       0x003a   100   100   000    Old_age   Always       -       0
190 Unknown_Attribute       0x0022   066   056   045    Old_age   Always       -       656539682
194 Temperature_Celsius     0x0022   034   044   000    Old_age   Always       -       34 (Lifetime Min/Max 0/22)
195 Hardware_ECC_Recovered  0x001a   063   059   000    Old_age   Always       -       18356524
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x003e   200   200   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0000   100   253   000    Old_age   Offline      -       0
202 TA_Increase_Count       0x0032   100   253   000    Old_age   Always       -       0
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%     19898         -
# 2  Short offline       Completed without error       00%     19897         -
# 3  Short offline       Interrupted (host reset)      90%     19871         -
SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
Am I right to replace the sda-disk? Can I just plug it off the machine?
stefan