Timeline for Clarification on MySQL innodb_flush_method variable
Current License: CC BY-SA 4.0
15 events
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| Apr 24, 2021 at 20:54 | history | edited | RolandoMySQLDBA | CC BY-SA 4.0 |
Corrected Spelling; Updated Formatting; hyperlinked inode for definition
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| Sep 9, 2014 at 17:17 | comment | added | noonex | I reference mainly to log writes from this part of manual "uses O_SYNC to open and flush the log files". That should mean that all writes to log are synchronous. And log writes is the thing which limits performace in short run (data writes may be delayed for long time and merged/optimized/etc) | |
| Sep 8, 2014 at 11:41 | comment | added | RolandoMySQLDBA |
@noonex According to en.wikipedia.org/wiki/Sync_(Unix), The related system call fsync() commits just the buffered data relating to a specified file descriptor. fdatasync() is also available to write out just the changes made to the data in the file, and not necessarily the file's related metadata. (That Wiki was last updated July 28, 2014).
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| Sep 8, 2014 at 11:36 | comment | added | RolandoMySQLDBA |
@noonex fdatasync() is synchronous for its data, not its metadata. According to informit.com/articles/article.aspx?p=23618&seqNum=5, This means that in principal, fdatasync can execute faster than fsync because it needs to force only one disk write instead of two. However, in current versions of Linux, these two system calls actually do the same thing, both updating the file's modification time. At the time I wrote my post 3.5 yrs ago, it was true, especially with older versions of Linux.
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| Sep 8, 2014 at 7:43 | comment | added | noonex | O_DSYNC is synchronous write, how can you conclude that it is faster that asynchronous + fsync? | |
| Sep 10, 2012 at 15:13 | history | edited | RolandoMySQLDBA | CC BY-SA 3.0 |
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| Mar 21, 2011 at 21:28 | history | edited | RolandoMySQLDBA | CC BY-SA 2.5 |
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| Mar 21, 2011 at 21:26 | comment | added | RolandoMySQLDBA | Thank you for clarifying that, Morgan. I'll correct this. | |
| Mar 21, 2011 at 21:00 | comment | added | Morgan Tocker | Worth pointing out: O_DIRECT is only used on the table-space files, not on the logs. Also - whether O_DIRECT is going to be useful or not depends on the hardware. I linked to an open documentation bug as a comment to the author's question. | |
| Mar 11, 2011 at 20:16 | history | edited | RolandoMySQLDBA | CC BY-SA 2.5 |
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| Mar 11, 2011 at 19:24 | vote | accept | Derek Downey | ||
| Mar 5, 2011 at 17:21 | history | undeleted | RolandoMySQLDBA | ||
| Mar 5, 2011 at 17:21 | history | edited | RolandoMySQLDBA | CC BY-SA 2.5 |
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| Mar 4, 2011 at 20:40 | history | deleted | RolandoMySQLDBA | ||
| Mar 4, 2011 at 20:33 | history | answered | RolandoMySQLDBA | CC BY-SA 2.5 |