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| author | Keith Bostic <keith@wiredtiger.com> | 2013-05-06 10:01:59 -0400 |
|---|---|---|
| committer | Keith Bostic <keith@wiredtiger.com> | 2013-05-06 10:01:59 -0400 |
| commit | 86584354b9d569e0a1486c9158f3ad95bbf81499 (patch) | |
| tree | c880b8074d2e3f9b2454ded55de7507d48717da4 /src | |
| parent | a2d6cc34deaa39c52629f05974338b25bbd36fe9 (diff) | |
| download | mongo-86584354b9d569e0a1486c9158f3ad95bbf81499.tar.gz | |
Document that direct_io=[data] (O_DIRECT for data files) implies that you
should turn off mmap (mmap=false), and utilities used to copy backup files
should probably also specify O_DIRECT. Ref #526.
Diffstat (limited to 'src')
| -rw-r--r-- | src/docs/hot_backup.dox | 6 | ||||
| -rw-r--r-- | src/include/wiredtiger.in | 10 |
2 files changed, 14 insertions, 2 deletions
diff --git a/src/docs/hot_backup.dox b/src/docs/hot_backup.dox index 981c1053d85..d0fc402efbb 100644 --- a/src/docs/hot_backup.dox +++ b/src/docs/hot_backup.dox @@ -55,4 +55,10 @@ have been copied before the cursor is closed. can be created, but no checkpoints can be deleted. This may result in significant file growth. +- Many Linux systems do not support mixing \c O_DIRECT and memory +mapping or normal I/O to the same file. If \c O_DIRECT is configured +for data files on Linux systems (using the wiredtiger_open \c direct_io +configuration), the utilities used to copy the database files should +probably also specify \c O_DIRECT when configuring their file access. + */ diff --git a/src/include/wiredtiger.in b/src/include/wiredtiger.in index be499ee500b..13ad9a37d12 100644 --- a/src/include/wiredtiger.in +++ b/src/include/wiredtiger.in @@ -1337,8 +1337,14 @@ struct __wt_connection { * @config{create, create the database if it does not exist., a boolean flag; * default \c false.} * @config{direct_io, Use \c O_DIRECT to access files. Options are given as a - * list\, such as <code>"direct_io=[data]"</code>., a list\, with values chosen - * from the following options: \c "data"\, \c "log"; default empty.} + * list\, such as <code>"direct_io=[data]"</code>. Many Linux systems do not + * support mixing \c O_DIRECT and memory mapping or normal I/O to the same file. + * If \c O_DIRECT is configured for data files on Linux systems\, memory mapping + * should probably be turned off using the \c mmap=false configuration string + * and any utilities used to copy the database files for the purposes of hot + * backup should probably also specify \c O_DIRECT when configuring their file + * access., a list\, with values chosen from the following options: \c "data"\, + * \c "log"; default empty.} * @config{error_prefix, prefix string for error messages., a string; default * empty.} * @config{eviction_dirty_target, continue evicting until the cache has less |