pg_verifybackup(1) PostgreSQL 13.3 Documentation pg_verifybackup(1)
NAME
pg_verifybackup - verify the integrity of a base backup of a PostgreSQL
cluster
SYNOPSIS
pg_verifybackup [option...]
DESCRIPTION
pg_verifybackup is used to check the integrity of a database cluster
backup taken using pg_basebackup against a backup_manifest generated by
the server at the time of the backup. The backup must be stored in the
"plain" format; a "tar" format backup can be checked after extracting
it.
It is important to note that the validation which is performed by
pg_verifybackup does not and cannot include every check which will be
performed by a running server when attempting to make use of the
backup. Even if you use this tool, you should still perform test
restores and verify that the resulting databases work as expected and
that they appear to contain the correct data. However, pg_verifybackup
can detect many problems that commonly occur due to storage problems or
user error.
Backup verification proceeds in four stages. First, pg_verifybackup
reads the backup_manifest file. If that file does not exist, cannot be
read, is malformed, or fails verification against its own internal
checksum, pg_verifybackup will terminate with a fatal error.
Second, pg_verifybackup will attempt to verify that the data files
currently stored on disk are exactly the same as the data files which
the server intended to send, with some exceptions that are described
below. Extra and missing files will be detected, with a few exceptions.
This step will ignore the presence or absence of, or any modifications
to, postgresql.auto.conf, standby.signal, and recovery.signal, because
it is expected that these files may have been created or modified as
part of the process of taking the backup. It also won't complain about
a backup_manifest file in the target directory or about anything inside
pg_wal, even though these files won't be listed in the backup manifest.
Only files are checked; the presence or absence of directories is not
verified, except indirectly: if a directory is missing, any files it
should have contained will necessarily also be missing.
Next, pg_verifybackup will checksum all the files, compare the
checksums against the values in the manifest, and emit errors for any
files for which the computed checksum does not match the checksum
stored in the manifest. This step is not performed for any files which
produced errors in the previous step, since they are already known to
have problems. Files which were ignored in the previous step are also
ignored in this step.
Finally, pg_verifybackup will use the manifest to verify that the
write-ahead log records which will be needed to recover the backup are
present and that they can be read and parsed. The backup_manifest
contains information about which write-ahead log records will be
needed, and pg_verifybackup will use that information to invoke
pg_waldump to parse those write-ahead log records. The --quiet flag
will be used, so that pg_waldump will only report errors, without
producing any other output. While this level of verification is
sufficient to detect obvious problems such as a missing file or one
whose internal checksums do not match, they aren't extensive enough to
detect every possible problem that might occur when attempting to
recover. For instance, a server bug that produces write-ahead log
records that have the correct checksums but specify nonsensical actions
can't be detected by this method.
Note that if extra WAL files which are not required to recover the
backup are present, they will not be checked by this tool, although a
separate invocation of pg_waldump could be used for that purpose. Also
note that WAL verification is version-specific: you must use the
version of pg_verifybackup, and thus of pg_waldump, which pertains to
the backup being checked. In contrast, the data file integrity checks
should work with any version of the server that generates a
backup_manifest file.
OPTIONS
pg_verifybackup accepts the following command-line arguments:
-e
--exit-on-error
Exit as soon as a problem with the backup is detected. If this
option is not specified, pg_verifybackup will continue checking the
backup even after a problem has been detected, and will report all
problems detected as errors.
-i path
--ignore=path
Ignore the specified file or directory, which should be expressed
as a relative path name, when comparing the list of data files
actually present in the backup to those listed in the
backup_manifest file. If a directory is specified, this option
affects the entire subtree rooted at that location. Complaints
about extra files, missing files, file size differences, or
checksum mismatches will be suppressed if the relative path name
matches the specified path name. This option can be specified
multiple times.
-m path
--manifest-path=path
Use the manifest file at the specified path, rather than one
located in the root of the backup directory.
-n
--no-parse-wal
Don't attempt to parse write-ahead log data that will be needed to
recover from this backup.
-q
--quiet
Don't print anything when a backup is successfully verified.
-s
--skip-checksums
Do not verify data file checksums. The presence or absence of files
and the sizes of those files will still be checked. This is much
faster, because the files themselves do not need to be read.
-w path
--wal-directory=path
Try to parse WAL files stored in the specified directory, rather
than in pg_wal. This may be useful if the backup is stored in a
separate location from the WAL archive.
Other options are also available:
-V
--version
Print the pg_verifybackup version and exit.
-?
--help
Show help about pg_verifybackup command line arguments, and exit.
EXAMPLES
To create a base backup of the server at mydbserver and verify the
integrity of the backup:
$ pg_basebackup -h mydbserver -D /usr/local/pgsql/data
$ pg_verifybackup /usr/local/pgsql/data
To create a base backup of the server at mydbserver, move the manifest
somewhere outside the backup directory, and verify the backup:
$ pg_basebackup -h mydbserver -D /usr/local/pgsql/backup1234
$ mv /usr/local/pgsql/backup1234/backup_manifest /my/secure/location/backup_manifest.1234
$ pg_verifybackup -m /my/secure/location/backup_manifest.1234 /usr/local/pgsql/backup1234
To verify a backup while ignoring a file that was added manually to the
backup directory, and also skipping checksum verification:
$ pg_basebackup -h mydbserver -D /usr/local/pgsql/data
$ edit /usr/local/pgsql/data/note.to.self
$ pg_verifybackup --ignore=note.to.self --skip-checksums /usr/local/pgsql/data
SEE ALSO
pg_basebackup(1)
PostgreSQL 13.3 2021 pg_verifybackup(1)
postgresql 13.3 - Generated Tue Jun 22 09:09:36 CDT 2021