Hi Cory,
We have zero_damaged_pages parameter in PostgreSQL configuration,by default it is set be off.
To recover data from corrupted table,we can turn on this parameter as a super user and populate new table using dump or copy utility.
Note : The damaged pages we can't recover from table,it will set to 0 and it will skip while fetching data from table.
Please follow below steps, if decided to recover data from corrupted table.
Sample case :
[postgres@instructor ~]$ /usr/local/pgsql/bin/psql
psql (9.4rc1)
Type "help" for help.
postgres=# select count(*) from test;
ERROR: invalid page in block 7 of relation base/13003/16384
postgres=# show zero_damaged_pages;
zero_damaged_pages
--------------------
off
(1 row)
postgres=# set zero_damaged_pages=on;
SET
postgres=# show zero_damaged_pages;
zero_damaged_pages
--------------------
on
(1 row)
postgres=# select count(*) from test;
WARNING: invalid page in block 7 of relation base/13003/16384; zeroing out page
WARNING: invalid page in block 8 of relation base/13003/16384; zeroing out page
WARNING: invalid page in block 9 of relation base/13003/16384; zeroing out page
WARNING: invalid page in block 10 of relation base/13003/16384; zeroing out page
WARNING: invalid page in block 11 of relation base/13003/16384; zeroing out page
WARNING: invalid page in block 12 of relation base/13003/16384; zeroing out page
WARNING: invalid page in block 13 of relation base/13003/16384; zeroing out page
count
--------
979163
(1 row)
On Tue, Dec 23, 2014 at 8:47 AM, Cory Zue <czue@xxxxxxxxxx> 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-bitHow you installed PostgreSQL:from standard package installerChanges made to the settings in the postgresql.conf file:name | current_setting | source------------------------------+-----------------------------+----------------------checkpoint_completion_target | 0.9 | configuration filecheckpoint_segments | 32 | configuration filecheckpoint_timeout | 15min | configuration fileDateStyle | ISO, MDY | configuration filedefault_text_search_config | pg_catalog.english | configuration fileeffective_cache_size | 1GB | configuration filelc_messages | en_US.UTF-8 | configuration filelc_monetary | en_US.UTF-8 | configuration filelc_numeric | en_US.UTF-8 | configuration filelc_time | en_US.UTF-8 | configuration filelog_checkpoints | on | configuration filelog_connections | off | configuration filelog_destination | csvlog | configuration filelog_directory | /opt/data/pgsql/data/pg_log | configuration filelog_disconnections | off | configuration filelog_duration | on | configuration filelog_filename | postgres-%Y-%m-%d_%H%M%S | configuration filelog_lock_waits | on | configuration filelog_min_duration_statement | 250ms | configuration filelog_rotation_age | 1d | configuration filelog_rotation_size | 1GB | configuration filelog_temp_files | 0 | configuration filelog_timezone | Asia/Kolkata | command linelog_truncate_on_rotation | on | configuration filelogging_collector | on | configuration filemaintenance_work_mem | 768MB | configuration filemax_connections | 500 | configuration filemax_stack_depth | 2MB | environment variableport | 5432 | command lineshared_buffers | 4GB | configuration filessl | on | configuration fileTimeZone | Asia/Kolkata | command linetimezone_abbreviations | Default | command linewal_buffers | 16MB | configuration filework_mem | 48MB | configuration fileIt's also probably worth noting that postgres is installed on an encrypted volume which is mounted using ecryptfs.Operating system and version:RedHatEnterpriseServer, version 6.6What 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=offin 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
