A prepared backup from Mariabackup does not really need to contain any
redo log file, because all log will have been applied to the data files.
When the user copies a prepared backup to a data directory (overwriting
existing files), it could happen that the data directory already contained
redo log files from the past. mariabackup --copy-back) would delete the
old redo log files, but a user’s own copying script might not do that.
To prevent corruption caused by mixing an old redo log file with data
files from a backup, starting with MDEV-13311, Mariabackup would create
a zero-length ib_logfile0 that would prevent startup.
Actually, there is no need to prevent InnoDB from starting up when a
single zero-length file ib_logfile0 is present. Only if there exist
multiple data files of different lengths, then we should refuse to
start up due to inconsistency. A single zero-length ib_logfile0 should
be treated as if the log files were missing: create new log files
according to the configuration.
open_log_file(): Remove. There is no need to open the log files
at this point, because os_file_get_status() already determined
the size of the file.
innobase_start_or_create_for_mysql(): Move the creation of new
log files a little later, not when finding out that the first log
file does not exist, but after finding out that it does not exist
or it exists as a zero-length file.
Mariabackup 10.2.7 would delete the redo log files after a successful
--prepare operation. If the user is manually copying the prepared files
instead of using the --copy-back option, it could happen that some old
redo log file would be preserved in the restored location. These old
redo log files could cause corruption of the restored data files when
the server is started up.
We prevent this scenario by creating a "poisoned" redo log file
ib_logfile0 at the end of the --prepare step. The poisoning consists
of simply truncating the file to an empty file. InnoDB will refuse
to start up on an empty redo log file.
copy_back(): Delete all redo log files in the target if the source
file ib_logfile0 is empty. (Previously we did this if the source
file is missing.)
SRV_OPERATION_RESTORE_EXPORT: A new variant of SRV_OPERATION_RESTORE
when the --export option is specified. In this mode, we will keep
deleting all redo log files, instead of truncating the first one.
delete_log_files(): Add a parameter for the first file to delete,
to be passed as 0 or 1.
innobase_start_or_create_for_mysql(): In mariabackup --prepare,
tolerate an empty ib_logfile0 file. Otherwise, require the first
redo log file to be longer than 4 blocks (2048 bytes). Unless
--export was specified, truncate the first log file at the
end of --prepare.
In Mariabackup, we would want the backed-up redo log file size to be
a multiple of 512 bytes, or OS_FILE_LOG_BLOCK_SIZE. However, at startup,
InnoDB would be picky, requiring the file size to be a multiple of
innodb_page_size.
Furthermore, InnoDB would require the parameter to be a multiple of
one megabyte, while the minimum granularity is 512 bytes. Because
the data-file-oriented fil_io() API is being used for writing the
InnoDB redo log, writes will for now require innodb_log_file_size to
be a multiple of the maximum innodb_page_size (65536 bytes).
To complicate matters, InnoDB startup divided srv_log_file_size by
UNIV_PAGE_SIZE, so that initially, the unit was bytes, and later it
was innodb_page_size. We will simplify this and keep srv_log_file_size
in bytes at all times.
innobase_log_file_size: Remove. Remove some obsolete checks against
overflow on 32-bit systems. srv_log_file_size is always 64 bits, and
the maximum size 512GiB in multiples of innodb_page_size always fits
in ulint (which is 32 or 64 bits). 512GiB would be 8,388,608*64KiB or
134,217,728*4KiB.
log_init(): Remove the parameter file_size that was always passed as
srv_log_file_size.
log_set_capacity(): Add a parameter for passing the requested file size.
srv_log_file_size_requested: Declare static in srv0start.cc.
create_log_file(), create_log_files(),
innobase_start_or_create_for_mysql(): Invoke fil_node_create()
with srv_log_file_size expressed in multiples of innodb_page_size.
innobase_start_or_create_for_mysql(): Require the redo log file sizes
to be multiples of 512 bytes.
1. Special mode to search in error logs: if SEARCH_RANGE is not set,
the file is considered an error log and the search is performed
since the last CURRENT_TEST: line
2. Number of matches is printed too. "FOUND 5 /foo/ in bar".
Use greedy .* at the end of the pattern if number of matches
isn't stable. If nothing is found it's still "NOT FOUND",
not "FOUND 0".
3. SEARCH_ABORT specifies the prefix of the output.
Can be "NOT FOUND" or "FOUND" as before,
but also "FOUND 5 " if needed.
namely, restart_mysqld_with_option.inc and kill_and_restart_mysqld.inc -
use restart_mysqld.inc instead.
Also remove innodb_wl6501_crash_stripped.inc that wasn't used anywhere.
The InnoDB redo log consists of a list of files that logically form
a bigger file, as if the individual files were concatenated together.
The first file will always be written on redo log checkpoint, because
the two checkpoint pages are at the start of the single logical
redo log file.
There is no technical reason why InnoDB requires at least 2 files
to exist. Let us reduce the minimum number to 1. In that way,
restoring from backups will become easier, since InnoDB can directly
deal with a single backed-up redo log file.
A proper InnoDB shutdown after aborted startup was introduced
in commit 81b7fe9d38.
Also related to this is MDEV-11985, making read-only shutdown more robust.
If startup was aborted, there may exist recovered transactions that were
not rolled back. Relax the assertions accordingly.
Remove the debug parameter innodb_force_recovery_crash that was
introduced into MySQL 5.6 by me in WL#6494 which allowed InnoDB
to resize the redo log on startup.
Let innodb.log_file_size actually start up the server, but ensure
that the InnoDB storage engine refuses to start up in each of the
scenarios.
recv_scan_log_recs(): Remember if redo log apply is needed,
even if starting up in innodb_read_only mode.
recv_recovery_from_checkpoint_start_func(): Refuse
innodb_read_only startup if redo log apply is needed.
