DB_HOTBACKUP(1) BerkeleyDB Utilities DB_HOTBACKUP(1)
NAME
db_hotbackup - Create "hot backup" or "hot failover" snapshots
SYNOPSIS
db_hotbackup [-cDEguVv] [-d data_dir ...] [-h home] [-l log_dir] [-P
password] -b backup_dir
DESCRIPTION
The db_hotbackup utility creates "hot backup" or "hot failover" snap-
shots of Berkeley DB database environments.
The db_hotbackup utility performs the following steps:
1. Sets the DB_HOTBACKUP_IN_PROGRESS flag in the home database
environment.
2. If the -c option is specified, checkpoint the source home
database environment, and remove any unnecessary log files.
3. If the target directory for the backup does not exist, it is
created with mode read-write-execute for the owner.
If the target directory for the backup does exist and the -u
option was specified, all log files in the target directory
are removed; if the -u option was not specified, all files in
the target directory are removed.
4. If the -u option was not specified, copy application-specific
files found in the database environment home directory, or
any directory specified using the -d option, into the target
directory for the backup.
5. Copy all log files found in the directory specified by the -l
option (or in the database environment home directory, if no
-l option was specified), into the target directory for the
backup.
6. Perform catastrophic recovery on the hot backup.
7. Remove any unnecessary log files from the hot backup.
8. Reset the DB_HOTBACKUP_IN_PROGRESS flag in the environment.
The db_hotbackup utility does not resolve pending transactions that are
in the prepared state. Applications that use DB_TXN->prepare should
specify DB_RECOVER_FATAL when opening the environment, and run
DB_ENV->txn_recover to resolve any pending transactions, when failing
over to the hot backup.
OPTIONS
-b backup_dir
Specify the target directory for the backup.
-c Before performing the snapshot, checkpoint the source database
environment and remove any log files that are no longer required
in that environment. To avoid making catastrophic failure
impossible, log file removal must be integrated with log file
archival.
Care should be taken with the -c option, where the db_hotbackup
MUST be run by the same user that owns the database. If db_hot-
backup is run by a user different to the owner of the database,
a new log file owned by this user might be created, making it
impossible to use the database for its owner.
-D Use the data and log directories listed in a DB_CONFIG configu-
ration file in the source directory. This option has four
effects:
1. The specified data and log directories will be created rela-
tive to the target directory, with mode read-write-execute
owner, if they do not already exist.
2. In step #3 above, all files in any source data directories
specified in the DB_CONFIG file will be copied to the target
data directories.
3. In step #4 above, log files will be copied from any log
directory specified in the DB_CONFIG file, instead of from
the default locations.
4. The DB_CONFIG configuration file will be copied from the
source directory to the target directory, and subsequently
used for configuration if recovery is run in the target
directory.
Care should be taken with the -D option where data and log
directories are named relative to the source directory but are
not subdirectories (that is, the name includes the element "..")
Specifically, the constructed target directory names must be
meaningful and distinct from the source directory names, other-
wise running recovery in the target directory might corrupt the
source data files.
It is an error to use absolute pathnames for data or log direc-
tories in this mode, as the DB_CONFIG configuration file copied
into the target directory would then point at the source direc-
tories and running recovery would corrupt the source data files.
-d data_dir
Specify one or more source directories that contain databases;
if none is specified, the database environment home directory
will be searched for database files. As database files are
copied into a single backup directory, files named the same,
stored in different source directories, could overwrite each
other when copied into the backup directory.
-F Directly copy from the filesystem. This option can CORRUPT the
backup if used while the environment is active and the operating
system does not support atomic file system reads. This option
is known to be safe only on UNIX systems, not Linux or Windows
systems.
-h home
Specify the source directory for the backup, that is, the data-
base environment home directory.
-l log_dir
Specify a source directory that contains log files; if none is
specified, the database environment home directory will be
searched for log files.
-P password
Specify an environment password. Although Berkeley DB utilities
overwrite password strings as soon as possible, be aware there
may be a window of vulnerability on systems where unprivileged
users can see command-line arguments or where utilities are not
able to overwrite the memory containing the command-line argu-
ments.
-u Update a pre-existing hot backup snapshot by copying in new log
files. If the -u option is specified, no databases will be
copied into the target directory.
-V Write the library version number to the standard output, and
exit.
-v Run in verbose mode, listing operations as they are done.
-D Use the data directories listed in the DB_CONFIG configuration
file in the source directory. This option has three effects:
First, if they do not already exist, the specified data directo-
ries will be created relative to the target directory (with mode
read-write-execute owner). Second, all files in the source data
directories will be copied to the target data directories. If
the DB_CONFIG file specifies one or more absolute pathnames,
files in those source directories will be copied to the top-
level target directory. Third, the DB_CONFIG configuration file
will be copied from the +source directory to the target direc-
tory, and subsequently used for configuration if recovery is run
in the target directory.
Care should be taken with the -D option and data directories which are
named relative to the source directory but are not subdirectories (that
is, the name includes the element "..") Specifically, the constructed
target directory names must be meaningful and distinct from the source
directory names, otherwise running recovery in the target directory
might corrupt the source data files.
It is an error to use absolute pathnames for data directories or the
log directory in this mode, as the DB_CONFIG configuration file copied
into the target directory would then point at the source directories
and running recovery would corrupt the source data files.
The db_hotbackup utility uses a Berkeley DB environment (as described
for the -h option, the environment variable DB_HOME, or because the
utility was run in a directory containing a Berkeley DB environment).
In order to avoid environment corruption when using a Berkeley DB envi-
ronment, db_hotbackup should always be given the chance to detach from
the environment and exit gracefully. To cause db_hotbackup to release
all environment resources and exit cleanly, send it an interrupt signal
(SIGINT).
EXIT STATUS
The db_hotbackup utility exits 0 on success, and >0 if an error occurs.
ENVIRONMENT
DB_HOME
If the -h option is not specified and the environment variable
DB_HOME is set, it is used as the path of the database home, as
described in DB_ENV->open.
SEE ALSO
db_archive(1) db_checkpoint(1) db_deadlock(1) db_dump(1) db_log_ver-
ify(1) db_load(1) db_printlog(1) db_recover(1) db_replicate(1)
db_stat(1) db_tuner(1) db_upgrade(1) db_verify(1)
BerkeleyDB 5.3.21 06 December 2016 DB_HOTBACKUP(1)
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