Commit c260366a authored by unknown's avatar unknown

manual.texi:

  Make InnoDB startup option samples easier to understand, recommend not setting log files too big, because recovery slow


Docs/manual.texi:
  Make InnoDB startup option samples easier to understand, recommend not setting log files too big, because recovery slow
parent 7b1ca932
......@@ -36313,23 +36313,37 @@ the configuration file @file{my.cnf}. @xref{Option files}.
The only required parameter to use InnoDB is @code{innodb_data_file_path},
but you should set others if you want to get a better performance.
Suppose you have a Windows NT machine with 128 MB RAM and a single 10 GB
Suppose you have a Windows NT computer with 128 MB RAM and a single 10 GB
hard disk. Below is an example of possible configuration parameters in
@file{my.cnf} for InnoDB:
@example
innodb_data_file_path = ibdata1:2000M;ibdata2:2000M
[mysqld]
# You can write your other MySQL server options here
# ...
#
innodb_data_home_dir = c:\ibdata
set-variable = innodb_mirrored_log_groups=1
# Data files must be able to
# hold your data and indexes
innodb_data_file_path = ibdata1:2000M;ibdata2:2000M
# Set buffer pool size to 50 - 80 %
# of your computer's memory
set-variable = innodb_buffer_pool_size=70M
set-variable = innodb_additional_mem_pool_size=10M
innodb_log_group_home_dir = c:\iblogs
# .._log_arch_dir must be the same
# as .._log_group_home_dir
innodb_log_arch_dir = c:\iblogs
innodb_log_archive=0
set-variable = innodb_log_files_in_group=3
set-variable = innodb_log_file_size=30M
# Set the log file size to about
# 15 % of the buffer pool size
set-variable = innodb_log_file_size=10M
set-variable = innodb_log_buffer_size=8M
# Set ..flush_log_at_trx_commit to
# 0 if you can afford losing
# a few last transactions
innodb_flush_log_at_trx_commit=1
innodb_log_arch_dir = c:\iblogs
innodb_log_archive=0
set-variable = innodb_buffer_pool_size=80M
set-variable = innodb_additional_mem_pool_size=10M
set-variable = innodb_file_io_threads=4
set-variable = innodb_lock_wait_timeout=50
@end example
......@@ -36340,27 +36354,44 @@ to be >= 10 MB.
InnoDB does not create directories:
you have to create them yourself.
Suppose you have a Linux machine with 512 MB RAM and
Suppose you have a Linux computer with 512 MB RAM and
three 20 GB hard disks (at directory paths @file{/},
@file{/dr2} and @file{/dr3}).
Below is an example of possible configuration parameters in @file{my.cnf} for
InnoDB:
@example
innodb_data_file_path = ibdata/ibdata1:2000M;dr2/ibdata/ibdata2:2000M
[mysqld]
# You can write your other MySQL server options here
# ...
#
innodb_data_home_dir = /
set-variable = innodb_mirrored_log_groups=1
innodb_log_group_home_dir = /dr3
# Data files must be able to
# hold your data and indexes
innodb_data_file_path = ibdata/ibdata1:2000M;dr2/ibdata/ibdata2:2000M
# Set buffer pool size to 50 - 80 %
# of your computer's memory
set-variable = innodb_buffer_pool_size=350M
set-variable = innodb_additional_mem_pool_size=20M
innodb_log_group_home_dir = /dr3/iblogs
# .._log_arch_dir must be the same
# as .._log_group_home_dir
innodb_log_arch_dir = /dr3/iblogs
innodb_log_archive=0
set-variable = innodb_log_files_in_group=3
# Set the log file size to about
# 15 % of the buffer pool size
set-variable = innodb_log_file_size=50M
set-variable = innodb_log_buffer_size=8M
# Set ..flush_log_at_trx_commit to
# 0 if you can afford losing
# a few last transactions
innodb_flush_log_at_trx_commit=1
innodb_log_arch_dir = /dr3/iblogs
innodb_log_archive=0
set-variable = innodb_buffer_pool_size=400M
set-variable = innodb_additional_mem_pool_size=20M
set-variable = innodb_file_io_threads=4
set-variable = innodb_lock_wait_timeout=50
#innodb_flush_method=fdatasync
#innodb_fast_shutdown=1
#set-variable = innodb_thread_concurrency=5
@end example
Note that we have placed the two data files on different disks.
......@@ -36374,6 +36405,10 @@ improve the performance of the database if all data is not placed
on the same physical disk. Putting log files on a different disk from
data is very often beneficial for performance.
The combined size of the log files MUST be < 4G in a 32-bit computer,
and to make recovery reasonably fast you should keep the combined size
smaller than the buffer pool size.
The meanings of the configuration parameters are the following:
@multitable @columnfractions .30 .70
......@@ -36397,7 +36432,9 @@ Number of log files in the log group. InnoDB writes to the files in a
circular fashion. Value 3 is recommended here.
@item @code{innodb_log_file_size} @tab
Size of each log file in a log group in megabytes. Sensible values range
from 1M to the size of the buffer pool specified below. The bigger the
from 1M to 1/nth of the size of the buffer pool specified below, where
n is the number of log files in the log group.
The bigger the
value, the less checkpoint flush activity is needed in the buffer pool,
saving disk i/o. But bigger log files also mean that recovery will be
slower in case of a crash. File size restriction as for a data file.
......@@ -37100,7 +37137,8 @@ to zero. InnoDB tries to flush the log anyway once in a second,
though the flush is not guaranteed.
@strong{4.}
Make your log files big, even as big as the buffer pool. When InnoDB
Make your log files big, the combined size
even as big as the buffer pool. When InnoDB
has written the log files full, it has to write the modified contents
of the buffer pool to disk in a checkpoint. Small log files will cause many
unnecessary disk writes. The drawback in big log files is that recovery
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