table marked as crashed and should be repaired
今天一台Windows的系统日志报了一长串的错误日志信息，每隔几秒就报一次。看了一下，都是一样的：
以下是使用MYSQL的自带工具myisamchk的解决办法：
a.myisamchk -c -r filename，失败
b.使用safe模式，失败
c.safe模式追加force参数，成功
这张表的数据量比较大，有1800多万，现在已经正常。 附myisamchk的使用方法：
Failed to write to mysql.general_log: Table 'general_log' is marked as crashed and should be repaired For more information, see Help and Support Center at http://www.mysql.com.进入数据库查看的时候就一直hang在那里，这个表是记录系统性能用的，之前跑了一个脚本专门往里面塞系统性能日志信息，表面看来表已经损坏，需要修复一下。修复之前原想备份一下，但是备份不成功，分析了下这个表，是个myisam引擎数据，另外存放的统计数据丢失也不要紧，故直接修复
以下是使用MYSQL的自带工具myisamchk的解决办法：
a.myisamchk -c -r filename，失败
b.使用safe模式，失败
c.safe模式追加force参数，成功
这张表的数据量比较大，有1800多万，现在已经正常。 附myisamchk的使用方法：
F:\mysql\bin>myisamchk --help
myisamchk Ver 2.7 for Win64 at x86
By Monty, for your professional use
This software comes with NO WARRANTY: see the PUBLIC for details.
Description, check and repair of MyISAM tables.
Used without options all tables on the command will be checked for errors
Usage: myisamchk [OPTIONS] tables[.MYI]
Global options:
-H, --HELP Display this help and exit.
-?, --help Display this help and exit.
-t, --tmpdir=path Path for temporary files. Multiple paths can be
specified, separated by semicolon (;), they will be used
in a round-robin fashion.
-s, --silent Only print errors. One can use two -s to make
myisamchk very silent.
-v, --verbose Print more information. This can be used with
--description and --check. Use many -v for more verbosity.
-V, --version Print version and exit.
-w, --wait Wait if table is locked.
Check options (check is the default action for myisamchk):
-c, --check Check table for errors.
-e, --extend-check Check the table VERY throughly. Only use this in
extreme cases as myisamchk should normally be able to
find out if the table is ok even without this switch.
-F, --fast Check only tables that haven't been closed properly.
-C, --check-only-changed
Check only tables that have changed since last check.
-f, --force Restart with '-r' if there are any errors in the table.
States will be updated as with '--update-state'.
-i, --information Print statistics information about table that is checked.
-m, --medium-check Faster than extend-check, but only finds 99.99% of
all errors. Should be good enough for most cases.
-U --update-state Mark tables as crashed if you find any errors.
-T, --read-only Don't mark table as checked.
Repair options (When using '-r' or '-o'):
-B, --backup Make a backup of the .MYD file as 'filename-time.BAK'.
--correct-checksum Correct checksum information for table.
-D, --data-file-length=# Max length of data file (when recreating data
file when it's full).
-e, --extend-check Try to recover every possible row from the data file
Normally this will also find a lot of garbage rows;
Don't use this option if you are not totally desperate.
-f, --force Overwrite old temporary files.
-k, --keys-used=# Tell MyISAM to update only some specific keys. # is a
bit mask of which keys to use. This can be used to
get faster inserts.
--max-record-length=#
Skip rows bigger than this if myisamchk can't allocate
memory to hold it.
-r, --recover Can fix almost anything except unique keys that aren't
unique.
-n, --sort-recover Forces recovering with sorting even if the temporary
file would be very big.
-p, --parallel-recover
Uses the same technique as '-r' and '-n', but creates
all the keys in parallel, in different threads.
-o, --safe-recover Uses old recovery method; Slower than '-r' but can
handle a couple of cases where '-r' reports that it
can't fix the data file.
--character-sets-dir=...
Directory where character sets are.
--set-collation=name
Change the collation used by the index.
-q, --quick Faster repair by not modifying the data file.
One can give a second '-q' to force myisamchk to
modify the original datafile in case of duplicate keys.
NOTE: Tables where the data file is currupted can't be
fixed with this option.
-u, --unpack Unpack file packed with myisampack.
Other actions:
-a, --analyze Analyze distribution of keys. Will make some joins in
MySQL faster. You can check the calculated distribution
by using '--description --verbose table_name'.
--stats_method=name Specifies how index statistics collection code should
treat NULLs. Possible values of name are "nulls_unequal"
(default for 4.1/5.0), "nulls_equal" (emulate 4.0), and
"nulls_ignored".
-d, --description Prints some information about table.
-A, --set-auto-increment[=value]
Force auto_increment to start at this or higher value
If no value is given, then sets the next auto_increment
value to the highest used value for the auto key + 1.
-S, --sort-index Sort index blocks. This speeds up 'read-next' in
applications.
-R, --sort-records=#
Sort records according to an index. This makes your
data much more localized and may speed up things
(It may be VERY slow to do a sort the first time!).
-b, --block-search=#
Find a record, a block at given offset belongs to.
Default options are read from the following files in the given order:
C:\WINDOWS\my.ini C:\WINDOWS\my.cnf C:\my.ini C:\my.cnf F:\mysql\my.ini F:\mysql
\my.cnf
The following groups are read: myisamchk
The following options may be given as the first argument:
--print-defaults Print the program argument list and exit.
--no-defaults Don't read default options from any option file.
--defaults-file=# Only read default options from the given file #.
--defaults-extra-file=# Read this file after the global files are read.
Variables (--variable-name=value)
and boolean options {FALSE|TRUE} Value (after reading options)
--------------------------------- ----------------------------------------
character-sets-dir (No default value)
data-file-length 0
keys-used 18446744073709551615
max-record-length 9223372036854775807
set-auto-increment 0
set-collation (No default value)
sort-records 0
tmpdir (No default value)
key-buffer-size 520192
key-cache-block-size 1024
myisam-block-size 1024
read-buffer-size 262136
write-buffer-size 262136
sort-buffer-size 2097144
sort-key-blocks 16
decode-bits 9
ft-min-word-len 4
ft-max-word-len 84
ft-stopword-file (No default value)
stats-method nulls_unequal