Обсуждение: help troubleshooting invalid page header error

Hi all,

Our postgres instance on one of our production machines has recently been returning errors of the form "DatabaseError: invalid page header in block 1 of relation base/16384/76623" from normal queries. I've been reading that these are often linked to hardware errors, but I would like to better understand what else it could be or how to determine that for sure. I've filled out the standard issue reporting template below. Any feedback or troubleshooting instructions would be much appreciated.

---

A description of what you are trying to achieve and what results you expect.:

Intermittent queries are failing with the error "DatabaseError: invalid page header in block 1 of relation base/16384/76623"

PostgreSQL version number you are running: 

PostgreSQL 8.4.13 on x86_64-redhat-linux-gnu, compiled by GCC gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), 64-bit

How you installed PostgreSQL: 

from standard package installer

Changes made to the settings in the postgresql.conf file:  

             name             |       current_setting       |        source        

------------------------------+-----------------------------+----------------------

 checkpoint_completion_target | 0.9                         | configuration file

 checkpoint_segments          | 32                          | configuration file

 checkpoint_timeout           | 15min                       | configuration file

 DateStyle                    | ISO, MDY                    | configuration file

 default_text_search_config   | pg_catalog.english          | configuration file

 effective_cache_size         | 1GB                         | configuration file

 lc_messages                  | en_US.UTF-8                 | configuration file

 lc_monetary                  | en_US.UTF-8                 | configuration file

 lc_numeric                   | en_US.UTF-8                 | configuration file

 lc_time                      | en_US.UTF-8                 | configuration file

 log_checkpoints              | on                          | configuration file

 log_connections              | off                         | configuration file

 log_destination              | csvlog                      | configuration file

 log_directory                | /opt/data/pgsql/data/pg_log | configuration file

 log_disconnections           | off                         | configuration file

 log_duration                 | on                          | configuration file

 log_filename                 | postgres-%Y-%m-%d_%H%M%S    | configuration file

 log_lock_waits               | on                          | configuration file

 log_min_duration_statement   | 250ms                       | configuration file

 log_rotation_age             | 1d                          | configuration file

 log_rotation_size            | 1GB                         | configuration file

 log_temp_files               | 0                           | configuration file

 log_timezone                 | Asia/Kolkata                | command line

 log_truncate_on_rotation     | on                          | configuration file

 logging_collector            | on                          | configuration file

 maintenance_work_mem         | 768MB                       | configuration file

 max_connections              | 500                         | configuration file

 max_stack_depth              | 2MB                         | environment variable

 port                         | 5432                        | command line

 shared_buffers               | 4GB                         | configuration file

 ssl                          | on                          | configuration file

 TimeZone                     | Asia/Kolkata                | command line

 timezone_abbreviations       | Default                     | command line

 wal_buffers                  | 16MB                        | configuration file

 work_mem                     | 48MB                        | configuration file

It's also probably worth noting that postgres is installed on an encrypted volume which is mounted using ecryptfs.

Operating system and version:

RedHatEnterpriseServer, version 6.6

What program you're using to connect to PostgreSQL:

Python (django)

 

Is there anything relevant or unusual in the PostgreSQL server logs?:

I see lots of instances of this error (and similar). I'm not sure what else I should be looking for.

What you were doing when the error happened / how to cause the error:

I haven't explicitly tried to reproduce it, but it seems to consistently happen with certain queries. However, the system was rebooted shortly before the errors started occuring. The system was rebooted because another database (elasticsearch) was having problems on the same machine and the reboot was to attempt to resolve things.

The EXACT TEXT of the error message you're getting, if there is one:

DatabaseError: invalid page header in block 1 of relation base/16384/76623

(block and relation numbers change)

Unfortunately, I'm not completely familiar with the CPU and disk/RAID configurations used on the server. However it is storing to a (software) encrypted volume as mentioned above.

• Have you ever set fsync=off in the postgresql config file?

No

• Have you had any unexpected power loss lately? Replaced a failed RAID disk? Had an operating system crash?

Not recently, though the system did reboot normally as described above.

• Have you run a file system check? (chkdsk / fsck)

No.

• Are there any error messages in the system logs? (unix/linux: dmesg, /var/log/syslog ;

I haven't seen anything obvious but I wasn't sure what to look for.

thanks,

Cory

Hi all,

Thanks for the responses. Chiru, I'm looking into your suggestion. 

Sameer, here is the kernel version info: 

Linux dimagi 2.6.32-431.20.5.el6.x86_64 #1 SMP Wed Jul 16 05:26:53 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

Does that seem like it could be a problematic version?

More generally - I'm still wondering whether I should chalk this failure up to a transient/random issue, or whether I should be more worried about the hardware on the machine. According to our diagnostic tools,  disk and memory are fine, but it's still not clear to me how it got into this state. Any general bits of information regarding the potential causes of these types of issues would be much appreciated.

thanks,

Cory

On Fri, Dec 26, 2014 at 6:55 AM, Sameer Kumar <sameer.kumar@ashnik.com> wrote:

On 23 Dec 2014 12:05, "Cory Zue" <czue@dimagi.com> wrote:
>
> Hi all,
>
> Our postgres instance on one of our production machines has recently been returning errors of the form "DatabaseError: invalid page header in block 1 of relation base/16384/76623" from normal queries. I've been reading that these are often linked to hardware errors, but I would like to better understand what else it could be or how to determine that for sure. I've filled out the standard issue reporting template below. Any feedback or troubleshooting instructions would be much appreciated.
>
> ---
> A description of what you are trying to achieve and what results you expect.:
>
> Intermittent queries are failing with the error "DatabaseError: invalid page header in block 1 of relation base/16384/76623"
>
> PostgreSQL version number you are running: 
>
> PostgreSQL 8.4.13 on x86_64-redhat-linux-gnu, compiled by GCC gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), 64-bit
>
> How you installed PostgreSQL: 
>
> from standard package installer
>
> Changes made to the settings in the postgresql.conf file:  
>
>
>              name             |       current_setting       |        source        
> ------------------------------+-----------------------------+----------------------
>  checkpoint_completion_target | 0.9                         | configuration file
>  checkpoint_segments          | 32                          | configuration file
>  checkpoint_timeout           | 15min                       | configuration file
>  DateStyle                    | ISO, MDY                    | configuration file
>  default_text_search_config   | pg_catalog.english          | configuration file
>  effective_cache_size         | 1GB                         | configuration file
>  lc_messages                  | en_US.UTF-8                 | configuration file
>  lc_monetary                  | en_US.UTF-8                 | configuration file
>  lc_numeric                   | en_US.UTF-8                 | configuration file
>  lc_time                      | en_US.UTF-8                 | configuration file
>  log_checkpoints              | on                          | configuration file
>  log_connections              | off                         | configuration file
>  log_destination              | csvlog                      | configuration file
>  log_directory                | /opt/data/pgsql/data/pg_log | configuration file
>  log_disconnections           | off                         | configuration file
>  log_duration                 | on                          | configuration file
>  log_filename                 | postgres-%Y-%m-%d_%H%M%S    | configuration file
>  log_lock_waits               | on                          | configuration file
>  log_min_duration_statement   | 250ms                       | configuration file
>  log_rotation_age             | 1d                          | configuration file
>  log_rotation_size            | 1GB                         | configuration file
>  log_temp_files               | 0                           | configuration file
>  log_timezone                 | Asia/Kolkata                | command line
>  log_truncate_on_rotation     | on                          | configuration file
>  logging_collector            | on                          | configuration file
>  maintenance_work_mem         | 768MB                       | configuration file
>  max_connections              | 500                         | configuration file
>  max_stack_depth              | 2MB                         | environment variable
>  port                         | 5432                        | command line
>  shared_buffers               | 4GB                         | configuration file
>  ssl                          | on                          | configuration file
>  TimeZone                     | Asia/Kolkata                | command line
>  timezone_abbreviations       | Default                     | command line
>  wal_buffers                  | 16MB                        | configuration file
>  work_mem                     | 48MB                        | configuration file
>
> It's also probably worth noting that postgres is installed on an encrypted volume which is mounted using ecryptfs.
>
> Operating system and version:
>
> RedHatEnterpriseServer, version 6.6
>
> What program you're using to connect to PostgreSQL:
>
> Python (django)
>  
> Is there anything relevant or unusual in the PostgreSQL server logs?:
>
> I see lots of instances of this error (and similar). I'm not sure what else I should be looking for.
>
> What you were doing when the error happened / how to cause the error:
>
> I haven't explicitly tried to reproduce it, but it seems to consistently happen with certain queries. However, the system was rebooted shortly before the errors started occuring. The system was rebooted because another database (elasticsearch) was having problems on the same machine and the reboot was to attempt to resolve things.
>
> The EXACT TEXT of the error message you're getting, if there is one:
>
> DatabaseError: invalid page header in block 1 of relation base/16384/76623
>
> (block and relation numbers change)
>
> Unfortunately, I'm not completely familiar with the CPU and disk/RAID configurations used on the server. However it is storing to a (software) encrypted volume as mentioned above.
>
> Have you ever set fsync=off in the postgresql config file?
> No
> Have you had any unexpected power loss lately? Replaced a failed RAID disk? Had an operating system crash?
> Not recently, though the system did reboot normally as described above.
> Have you run a file system check? (chkdsk / fsck)
> No.
> Are there any error messages in the system logs? (unix/linux: dmesg, /var/log/syslog ;
> I haven't seen anything obvious but I wasn't sure what to look for.
>

I guess you missed to provide the details and kernel version (rhel version and kernel level).
This will give you kernel patch level-

uname -a

I had once faced this issue and I was on a buggy patch of Linux kernel. I just had to update to latest patch. That worked for me.

Hi Cory,

After recovering table turn off zero_damaged_pages  parameter.

On Fri, Dec 26, 2014 at 9:13 PM, Cory Zue <czue@dimagi.com> wrote:

Hi all,

Thanks for the responses. Chiru, I'm looking into your suggestion. 

Sameer, here is the kernel version info: 

Linux dimagi 2.6.32-431.20.5.el6.x86_64 #1 SMP Wed Jul 16 05:26:53 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

Does that seem like it could be a problematic version?

More generally - I'm still wondering whether I should chalk this failure up to a transient/random issue, or whether I should be more worried about the hardware on the machine. According to our diagnostic tools,  disk and memory are fine, but it's still not clear to me how it got into this state. Any general bits of information regarding the potential causes of these types of issues would be much appreciated.

thanks,

Cory

On Fri, Dec 26, 2014 at 6:55 AM, Sameer Kumar <sameer.kumar@ashnik.com> wrote:

On 23 Dec 2014 12:05, "Cory Zue" <czue@dimagi.com> wrote:
>
> Hi all,
>
> Our postgres instance on one of our production machines has recently been returning errors of the form "DatabaseError: invalid page header in block 1 of relation base/16384/76623" from normal queries. I've been reading that these are often linked to hardware errors, but I would like to better understand what else it could be or how to determine that for sure. I've filled out the standard issue reporting template below. Any feedback or troubleshooting instructions would be much appreciated.
>
> ---
> A description of what you are trying to achieve and what results you expect.:
>
> Intermittent queries are failing with the error "DatabaseError: invalid page header in block 1 of relation base/16384/76623"
>
> PostgreSQL version number you are running: 
>
> PostgreSQL 8.4.13 on x86_64-redhat-linux-gnu, compiled by GCC gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), 64-bit
>
> How you installed PostgreSQL: 
>
> from standard package installer
>
> Changes made to the settings in the postgresql.conf file:  
>
>
>              name             |       current_setting       |        source        
> ------------------------------+-----------------------------+----------------------
>  checkpoint_completion_target | 0.9                         | configuration file
>  checkpoint_segments          | 32                          | configuration file
>  checkpoint_timeout           | 15min                       | configuration file
>  DateStyle                    | ISO, MDY                    | configuration file
>  default_text_search_config   | pg_catalog.english          | configuration file
>  effective_cache_size         | 1GB                         | configuration file
>  lc_messages                  | en_US.UTF-8                 | configuration file
>  lc_monetary                  | en_US.UTF-8                 | configuration file
>  lc_numeric                   | en_US.UTF-8                 | configuration file
>  lc_time                      | en_US.UTF-8                 | configuration file
>  log_checkpoints              | on                          | configuration file
>  log_connections              | off                         | configuration file
>  log_destination              | csvlog                      | configuration file
>  log_directory                | /opt/data/pgsql/data/pg_log | configuration file
>  log_disconnections           | off                         | configuration file
>  log_duration                 | on                          | configuration file
>  log_filename                 | postgres-%Y-%m-%d_%H%M%S    | configuration file
>  log_lock_waits               | on                          | configuration file
>  log_min_duration_statement   | 250ms                       | configuration file
>  log_rotation_age             | 1d                          | configuration file
>  log_rotation_size            | 1GB                         | configuration file
>  log_temp_files               | 0                           | configuration file
>  log_timezone                 | Asia/Kolkata                | command line
>  log_truncate_on_rotation     | on                          | configuration file
>  logging_collector            | on                          | configuration file
>  maintenance_work_mem         | 768MB                       | configuration file
>  max_connections              | 500                         | configuration file
>  max_stack_depth              | 2MB                         | environment variable
>  port                         | 5432                        | command line
>  shared_buffers               | 4GB                         | configuration file
>  ssl                          | on                          | configuration file
>  TimeZone                     | Asia/Kolkata                | command line
>  timezone_abbreviations       | Default                     | command line
>  wal_buffers                  | 16MB                        | configuration file
>  work_mem                     | 48MB                        | configuration file
>
> It's also probably worth noting that postgres is installed on an encrypted volume which is mounted using ecryptfs.
>
> Operating system and version:
>
> RedHatEnterpriseServer, version 6.6
>
> What program you're using to connect to PostgreSQL:
>
> Python (django)
>  
> Is there anything relevant or unusual in the PostgreSQL server logs?:
>
> I see lots of instances of this error (and similar). I'm not sure what else I should be looking for.
>
> What you were doing when the error happened / how to cause the error:
>
> I haven't explicitly tried to reproduce it, but it seems to consistently happen with certain queries. However, the system was rebooted shortly before the errors started occuring. The system was rebooted because another database (elasticsearch) was having problems on the same machine and the reboot was to attempt to resolve things.
>
> The EXACT TEXT of the error message you're getting, if there is one:
>
> DatabaseError: invalid page header in block 1 of relation base/16384/76623
>
> (block and relation numbers change)
>
> Unfortunately, I'm not completely familiar with the CPU and disk/RAID configurations used on the server. However it is storing to a (software) encrypted volume as mentioned above.
>
> Have you ever set fsync=off in the postgresql config file?
> No
> Have you had any unexpected power loss lately? Replaced a failed RAID disk? Had an operating system crash?
> Not recently, though the system did reboot normally as described above.
> Have you run a file system check? (chkdsk / fsck)
> No.
> Are there any error messages in the system logs? (unix/linux: dmesg, /var/log/syslog ;
> I haven't seen anything obvious but I wasn't sure what to look for.
>

I guess you missed to provide the details and kernel version (rhel version and kernel level).
This will give you kernel patch level-

uname -a

I had once faced this issue and I was on a buggy patch of Linux kernel. I just had to update to latest patch. That worked for me.

Hi Chiru,

I am trying to pg_dump the database to have a snapshot of the current state. I've turned on 'zero_damaged_pages' but pg_dump is still failing with an "invalid page header" error - this time from what looks like a sequence object that is auto-setting IDs on a table. Any advice on how to remove this error?

Here is the full query that's failing:

SELECT sequence_name, start_value, last_value, increment_by, CASE WHEN increment_by > 0 AND max_value = 9223372036854775807 THEN NULL      WHEN increment_by < 0 AND max_value = -1 THEN NULL      ELSE max_value END AS max_value, CASE WHEN increment_by > 0 AND min_value = 1 THEN NULL      WHEN increment_by < 0 AND min_value = -9223372036854775807 THEN NULL      ELSE min_value END AS min_value, cache_value, is_cycled, is_called from unfinishedsubmissionstub_id_seq

On Fri, Dec 26, 2014 at 2:35 PM, chiru r <chirupg@gmail.com> wrote:

Hi Cory,

After recovering table turn off zero_damaged_pages  parameter.

On Fri, Dec 26, 2014 at 9:13 PM, Cory Zue <czue@dimagi.com> wrote:

Hi all,

Thanks for the responses. Chiru, I'm looking into your suggestion. 

Sameer, here is the kernel version info: 

Linux dimagi 2.6.32-431.20.5.el6.x86_64 #1 SMP Wed Jul 16 05:26:53 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

Does that seem like it could be a problematic version?

More generally - I'm still wondering whether I should chalk this failure up to a transient/random issue, or whether I should be more worried about the hardware on the machine. According to our diagnostic tools,  disk and memory are fine, but it's still not clear to me how it got into this state. Any general bits of information regarding the potential causes of these types of issues would be much appreciated.

thanks,

Cory

On Fri, Dec 26, 2014 at 6:55 AM, Sameer Kumar <sameer.kumar@ashnik.com> wrote:

On 23 Dec 2014 12:05, "Cory Zue" <czue@dimagi.com> wrote:
>
> Hi all,
>
> Our postgres instance on one of our production machines has recently been returning errors of the form "DatabaseError: invalid page header in block 1 of relation base/16384/76623" from normal queries. I've been reading that these are often linked to hardware errors, but I would like to better understand what else it could be or how to determine that for sure. I've filled out the standard issue reporting template below. Any feedback or troubleshooting instructions would be much appreciated.
>
> ---
> A description of what you are trying to achieve and what results you expect.:
>
> Intermittent queries are failing with the error "DatabaseError: invalid page header in block 1 of relation base/16384/76623"
>
> PostgreSQL version number you are running: 
>
> PostgreSQL 8.4.13 on x86_64-redhat-linux-gnu, compiled by GCC gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), 64-bit
>
> How you installed PostgreSQL: 
>
> from standard package installer
>
> Changes made to the settings in the postgresql.conf file:  
>
>
>              name             |       current_setting       |        source        
> ------------------------------+-----------------------------+----------------------
>  checkpoint_completion_target | 0.9                         | configuration file
>  checkpoint_segments          | 32                          | configuration file
>  checkpoint_timeout           | 15min                       | configuration file
>  DateStyle                    | ISO, MDY                    | configuration file
>  default_text_search_config   | pg_catalog.english          | configuration file
>  effective_cache_size         | 1GB                         | configuration file
>  lc_messages                  | en_US.UTF-8                 | configuration file
>  lc_monetary                  | en_US.UTF-8                 | configuration file
>  lc_numeric                   | en_US.UTF-8                 | configuration file
>  lc_time                      | en_US.UTF-8                 | configuration file
>  log_checkpoints              | on                          | configuration file
>  log_connections              | off                         | configuration file
>  log_destination              | csvlog                      | configuration file
>  log_directory                | /opt/data/pgsql/data/pg_log | configuration file
>  log_disconnections           | off                         | configuration file
>  log_duration                 | on                          | configuration file
>  log_filename                 | postgres-%Y-%m-%d_%H%M%S    | configuration file
>  log_lock_waits               | on                          | configuration file
>  log_min_duration_statement   | 250ms                       | configuration file
>  log_rotation_age             | 1d                          | configuration file
>  log_rotation_size            | 1GB                         | configuration file
>  log_temp_files               | 0                           | configuration file
>  log_timezone                 | Asia/Kolkata                | command line
>  log_truncate_on_rotation     | on                          | configuration file
>  logging_collector            | on                          | configuration file
>  maintenance_work_mem         | 768MB                       | configuration file
>  max_connections              | 500                         | configuration file
>  max_stack_depth              | 2MB                         | environment variable
>  port                         | 5432                        | command line
>  shared_buffers               | 4GB                         | configuration file
>  ssl                          | on                          | configuration file
>  TimeZone                     | Asia/Kolkata                | command line
>  timezone_abbreviations       | Default                     | command line
>  wal_buffers                  | 16MB                        | configuration file
>  work_mem                     | 48MB                        | configuration file
>
> It's also probably worth noting that postgres is installed on an encrypted volume which is mounted using ecryptfs.
>
> Operating system and version:
>
> RedHatEnterpriseServer, version 6.6
>
> What program you're using to connect to PostgreSQL:
>
> Python (django)
>  
> Is there anything relevant or unusual in the PostgreSQL server logs?:
>
> I see lots of instances of this error (and similar). I'm not sure what else I should be looking for.
>
> What you were doing when the error happened / how to cause the error:
>
> I haven't explicitly tried to reproduce it, but it seems to consistently happen with certain queries. However, the system was rebooted shortly before the errors started occuring. The system was rebooted because another database (elasticsearch) was having problems on the same machine and the reboot was to attempt to resolve things.
>
> The EXACT TEXT of the error message you're getting, if there is one:
>
> DatabaseError: invalid page header in block 1 of relation base/16384/76623
>
> (block and relation numbers change)
>
> Unfortunately, I'm not completely familiar with the CPU and disk/RAID configurations used on the server. However it is storing to a (software) encrypted volume as mentioned above.
>
> Have you ever set fsync=off in the postgresql config file?
> No
> Have you had any unexpected power loss lately? Replaced a failed RAID disk? Had an operating system crash?
> Not recently, though the system did reboot normally as described above.
> Have you run a file system check? (chkdsk / fsck)
> No.
> Are there any error messages in the system logs? (unix/linux: dmesg, /var/log/syslog ;
> I haven't seen anything obvious but I wasn't sure what to look for.
>

I guess you missed to provide the details and kernel version (rhel version and kernel level).
This will give you kernel patch level-

uname -a

I had once faced this issue and I was on a buggy patch of Linux kernel. I just had to update to latest patch. That worked for me.

Hi Chiru,

I am trying to pg_dump the database to have a snapshot of the current state. I've turned on 'zero_damaged_pages' but pg_dump is still failing with an "invalid page header" error - this time from what looks like a sequence object that is auto-setting IDs on a table. Any advice on how to remove this error?

Here is the full query that's failing:

SELECT sequence_name, start_value, last_value, increment_by, CASE WHEN increment_by > 0 AND max_value = 9223372036854775807 THEN NULL      WHEN increment_by < 0 AND max_value = -1 THEN NULL      ELSE max_value END AS max_value, CASE WHEN increment_by > 0 AND min_value = 1 THEN NULL      WHEN increment_by < 0 AND min_value = -9223372036854775807 THEN NULL      ELSE min_value END AS min_value, cache_value, is_cycled, is_called from unfinishedsubmissionstub_id_seq

On Fri, Dec 26, 2014 at 2:35 PM, chiru r <chirupg@gmail.com> wrote:

Hi Cory,

After recovering table turn off zero_damaged_pages  parameter.

On Fri, Dec 26, 2014 at 9:13 PM, Cory Zue <czue@dimagi.com> wrote:

Hi all,

Thanks for the responses. Chiru, I'm looking into your suggestion. 

Sameer, here is the kernel version info: 

Linux dimagi 2.6.32-431.20.5.el6.x86_64 #1 SMP Wed Jul 16 05:26:53 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

Does that seem like it could be a problematic version?

More generally - I'm still wondering whether I should chalk this failure up to a transient/random issue, or whether I should be more worried about the hardware on the machine. According to our diagnostic tools,  disk and memory are fine, but it's still not clear to me how it got into this state. Any general bits of information regarding the potential causes of these types of issues would be much appreciated.

thanks,

Cory

On Fri, Dec 26, 2014 at 6:55 AM, Sameer Kumar <sameer.kumar@ashnik.com> wrote:

On 23 Dec 2014 12:05, "Cory Zue" <czue@dimagi.com> wrote:
>
> Hi all,
>
> Our postgres instance on one of our production machines has recently been returning errors of the form "DatabaseError: invalid page header in block 1 of relation base/16384/76623" from normal queries. I've been reading that these are often linked to hardware errors, but I would like to better understand what else it could be or how to determine that for sure. I've filled out the standard issue reporting template below. Any feedback or troubleshooting instructions would be much appreciated.
>
> ---
> A description of what you are trying to achieve and what results you expect.:
>
> Intermittent queries are failing with the error "DatabaseError: invalid page header in block 1 of relation base/16384/76623"
>
> PostgreSQL version number you are running: 
>
> PostgreSQL 8.4.13 on x86_64-redhat-linux-gnu, compiled by GCC gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), 64-bit
>
> How you installed PostgreSQL: 
>
> from standard package installer
>
> Changes made to the settings in the postgresql.conf file:  
>
>
>              name             |       current_setting       |        source        
> ------------------------------+-----------------------------+----------------------
>  checkpoint_completion_target | 0.9                         | configuration file
>  checkpoint_segments          | 32                          | configuration file
>  checkpoint_timeout           | 15min                       | configuration file
>  DateStyle                    | ISO, MDY                    | configuration file
>  default_text_search_config   | pg_catalog.english          | configuration file
>  effective_cache_size         | 1GB                         | configuration file
>  lc_messages                  | en_US.UTF-8                 | configuration file
>  lc_monetary                  | en_US.UTF-8                 | configuration file
>  lc_numeric                   | en_US.UTF-8                 | configuration file
>  lc_time                      | en_US.UTF-8                 | configuration file
>  log_checkpoints              | on                          | configuration file
>  log_connections              | off                         | configuration file
>  log_destination              | csvlog                      | configuration file
>  log_directory                | /opt/data/pgsql/data/pg_log | configuration file
>  log_disconnections           | off                         | configuration file
>  log_duration                 | on                          | configuration file
>  log_filename                 | postgres-%Y-%m-%d_%H%M%S    | configuration file
>  log_lock_waits               | on                          | configuration file
>  log_min_duration_statement   | 250ms                       | configuration file
>  log_rotation_age             | 1d                          | configuration file
>  log_rotation_size            | 1GB                         | configuration file
>  log_temp_files               | 0                           | configuration file
>  log_timezone                 | Asia/Kolkata                | command line
>  log_truncate_on_rotation     | on                          | configuration file
>  logging_collector            | on                          | configuration file
>  maintenance_work_mem         | 768MB                       | configuration file
>  max_connections              | 500                         | configuration file
>  max_stack_depth              | 2MB                         | environment variable
>  port                         | 5432                        | command line
>  shared_buffers               | 4GB                         | configuration file
>  ssl                          | on                          | configuration file
>  TimeZone                     | Asia/Kolkata                | command line
>  timezone_abbreviations       | Default                     | command line
>  wal_buffers                  | 16MB                        | configuration file
>  work_mem                     | 48MB                        | configuration file
>
> It's also probably worth noting that postgres is installed on an encrypted volume which is mounted using ecryptfs.
>
> Operating system and version:
>
> RedHatEnterpriseServer, version 6.6
>
> What program you're using to connect to PostgreSQL:
>
> Python (django)
>  
> Is there anything relevant or unusual in the PostgreSQL server logs?:
>
> I see lots of instances of this error (and similar). I'm not sure what else I should be looking for.
>
> What you were doing when the error happened / how to cause the error:
>
> I haven't explicitly tried to reproduce it, but it seems to consistently happen with certain queries. However, the system was rebooted shortly before the errors started occuring. The system was rebooted because another database (elasticsearch) was having problems on the same machine and the reboot was to attempt to resolve things.
>
> The EXACT TEXT of the error message you're getting, if there is one:
>
> DatabaseError: invalid page header in block 1 of relation base/16384/76623
>
> (block and relation numbers change)
>
> Unfortunately, I'm not completely familiar with the CPU and disk/RAID configurations used on the server. However it is storing to a (software) encrypted volume as mentioned above.
>
> Have you ever set fsync=off in the postgresql config file?
> No
> Have you had any unexpected power loss lately? Replaced a failed RAID disk? Had an operating system crash?
> Not recently, though the system did reboot normally as described above.
> Have you run a file system check? (chkdsk / fsck)
> No.
> Are there any error messages in the system logs? (unix/linux: dmesg, /var/log/syslog ;
> I haven't seen anything obvious but I wasn't sure what to look for.
>

I guess you missed to provide the details and kernel version (rhel version and kernel level).
This will give you kernel patch level-

uname -a

I had once faced this issue and I was on a buggy patch of Linux kernel. I just had to update to latest patch. That worked for me.