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Re: [Maria-discuss] fsync necessary for synchronous page flush?
by Xiaofei Du 11 May '15

11 May '15

Hi Jan, Thanks for clarification. I should have used synchronous write, instead of synchronous flush. My point is that I noticed for sync writes, fsync is called to force pages to be on persistent storage. while for AIO pages, fsync is not called to force pages to be on persistent storage. My question here is why fsync is required for sync IOs. Does InnoDB maintain a dirty page table? Is fsync called to guarantee the page to be on persistent storage so that the dirty page table can be updated? If this is the case, when is the dirty page table updated for asynchronous IOs? P.S. I couldn't find code for dirty page table. So I am not sure if InnoDB maintains a dirty page table for recovery. Could you please give me a pointer to related code and related resources? Thanks. Xiaofei On Wed, May 6, 2015 at 10:12 AM, Jan Lindström <jan.lindstrom(a)mariadb.com> wrote: > Hi, > > Terminology is little bit confusing here. Page flushing means that we have > done synchronous write to disk but that does not mean that write is > physically on device yet, therefore there is flush to force it to > persistent storage. > > R: Jan > > On Wed, May 6, 2015 at 12:57 AM, Xiaofei Du <xiaofei.du008(a)gmail.com> > wrote: > >> Hello, >> >> When a dirty page is flushed synchronously in buf_flush_write_block_low, >> fsync is called in the following snippet. I am wondering why >> we need this fsync for synchronous flush? The record should be in >> the log already, so recovery should be able to successfully redo it >> and apply to the disk during recovery. Maybe I am missing something here, >> please let me know if I am wrong. Thanks much! >> >> Xiaofei >> >> >> /* When doing single page flushing the IO is done synchronously and we >> flush the changes to disk only for the tablespace we are working on. */ if >> (sync) { ut_ad(flush_type == BUF_FLUSH_SINGLE_PAGE); fil_flush(buf_page_get_space(bpage)); >> /* true means we want to evict this page from the LRU list as well. */ >> buf_page_io_complete(bpage, true); } >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~maria-discuss >> Post to : maria-discuss(a)lists.launchpad.net >> Unsubscribe : https://launchpad.net/~maria-discuss >> More help : https://help.launchpad.net/ListHelp >> >> >

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[Maria-discuss] New Question: MariaDb Crashing after some wordpress posts
by AskMonty KB 10 May '15

10 May '15

Hello, A new question has been asked in "MariaDB Community" by nunocarapito. Please answer it at http://mariadb.com/kb/en/mariadb-crashing-after-some-wordpress-posts/ as the person asking the question may not be subscribed to the mailing list. -------------------------------- Hi there. I have 2 wordpress blogs in a host, both using mariaDB. Sometimes when I add a new post, DB crashes, and can't find the reason of that. I got a screenshot of the log (mariadb.log). http://i.imgur.com/fiwA7VE.png?1 I cant find out the reason of it. Can you guys give me any help? -------------------------------- To view or answer this question please visit: http://mariadb.com/kb/en/mariadb-crashing-after-some-wordpress-posts/

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[Maria-discuss] How to unsibscribe
by Vadim Pestovnikov 10 May '15

10 May '15

Hi all, Could you please advice me how to unsibscribe from this mailing list? Unfortunately folowing by this link Unsubscribe : https://launchpad.net/~maria-discuss I couldn't find how to do it. Thank you in advance.

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[Maria-discuss] MariaDB 10.0.19 now available
by Daniel Bartholomew 09 May '15

09 May '15

The MariaDB project is pleased to announce the immediate availability of MariaDB 10.0.19. This is a Stable (GA) release. See the Release Notes and Changelog for details. - - Links - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - MariaDB 10.0.19 - Release Notes: https://mariadb.com/kb/en/mariadb-10019-release-notes - Changelog: https://mariadb.com/kb/en/mariadb-10019-changelog - Downloads: https://downloads.mariadb.org/mariadb/10.0.19 About MariaDB 10.0: - https://mariadb.com/kb/en/what-is-mariadb-100/ APT and YUM Repository Configuration Generator: - https://downloads.mariadb.org/mariadb/repositories/ - - MariaDB Webinars - - - - - - - - - - - - - - - - - - - - - - - - - There are several upcoming MariaDB-focused webinars and many previously held ones available to watch on an on-demand basis at: - https://mariadb.com/news-events/webinars - - MariaDB Books - - - - - - - - - - - - - - - - - - - - - - - - - - There is an ever-growing library of MariaDB books available to help you get the most out of MariaDB. See the MariaDB Books page for details and links: - https://mariadb.com/kb/en/mariadb/books/ - - User Feedback plugin - - - - - - - - - - - - - - - - - - - - - - - MariaDB includes a User Feedback plugin. This plugin is disabled by default. If enabled, it submits basic, completely anonymous MariaDB usage information. This information is used by the developers to track trends in MariaDB usage to better guide development efforts. If you would like to help make MariaDB better, please add "feedback=ON" to your my.cnf or my.ini file! See http://mariadb.com/kb/en/user-feedback-plugin for more information. - - Quality - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The project always strives for quality, but in reality, nothing is perfect. Please take time to report any issues you encounter at: - http://mariadb.org/jira - - Support MariaDB - - - - - - - - - - - - - - - - - - - - - - - - - - If you would like to contribute to the MariaDB Foundation, please see the "contributing" and "donations" pages. We also have merchandise available in a cafepress store. All proceeds go to support the MariaDB Foundation. - https://mariadb.com/kb/en/contributing - https://mariadb.org/en/donate/ We hope you enjoy MariaDB! -- MariaDB Website - http://mariadb.org Twitter - http://twitter.com/mariadb Google+ - http://google.com/+mariadb Facebook - http://fb.com/MariaDB.dbms Knowledge Base - http://mariadb.com/kb

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[Maria-discuss] MariaDB 10.0.18 now available
by Daniel Bartholomew 08 May '15

08 May '15

The MariaDB project is pleased to announce the immediate availability of MariaDB 10.0.18. This is a Stable (GA) release. See the Release Notes and Changelog for details. - - Links - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - MariaDB 10.0.18 - Release Notes: https://mariadb.com/kb/en/mariadb-10018-release-notes - Changelog: https://mariadb.com/kb/en/mariadb-10018-changelog - Downloads: https://downloads.mariadb.org/mariadb/10.0.18 About MariaDB 10.0: - https://mariadb.com/kb/en/what-is-mariadb-100/ APT and YUM Repository Configuration Generator: - https://downloads.mariadb.org/mariadb/repositories/ - - MariaDB Webinars - - - - - - - - - - - - - - - - - - - - - - - - - There are several upcoming MariaDB-focused webinars and many previously held ones available to watch on an on-demand basis at: - https://mariadb.com/news-events/webinars - - MariaDB Books - - - - - - - - - - - - - - - - - - - - - - - - - - There is an ever-growing library of MariaDB books available to help you get the most out of MariaDB. See the MariaDB Books page for details and links: - https://mariadb.com/kb/en/mariadb/books/ - - User Feedback plugin - - - - - - - - - - - - - - - - - - - - - - - MariaDB includes a User Feedback plugin. This plugin is disabled by default. If enabled, it submits basic, completely anonymous MariaDB usage information. This information is used by the developers to track trends in MariaDB usage to better guide development efforts. If you would like to help make MariaDB better, please add "feedback=ON" to your my.cnf or my.ini file! See http://mariadb.com/kb/en/user-feedback-plugin for more information. - - Quality - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The project always strives for quality, but in reality, nothing is perfect. Please take time to report any issues you encounter at: - http://mariadb.org/jira - - Support MariaDB - - - - - - - - - - - - - - - - - - - - - - - - - - If you would like to contribute to the MariaDB Foundation, please see the "contributing" and "donations" pages. We also have merchandise available in a cafepress store. All proceeds go to support the MariaDB Foundation. - https://mariadb.com/kb/en/contributing - https://mariadb.org/en/donate/ We hope you enjoy MariaDB! -- MariaDB Website - http://mariadb.org Twitter - http://twitter.com/mariadb Google+ - http://google.com/+mariadb Facebook - http://fb.com/MariaDB.dbms Knowledge Base - http://mariadb.com/kb

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[Maria-discuss] innodb_file_per_table default setting in the online documentation
by Pantelis Theodosiou 08 May '15

08 May '15

I was looking for the default setting of this variable and the MariaDB documentation <https://mariadb.com/kb/en/mariadb/xtradbinnodb-server-system-variables/#inn…> has: > *Default Value:* OFF (>= MariaDB/MySQL 5.5.7), ON (MariaDB/MySQL 5.5.0 to 5.5.6) while MySQL documentation <http://dev.mysql.com/doc/refman/5.6/en/innodb-parameters.html#sysvar_innodb…> has (I think correctly): *Permitted Values* (<= 5.6.5) *Type* boolean* Default *OFF *Permitted Values* (>= 5.6.6) *Type *boolean* Default *ON So, I see two issues: - first, the changing version is 5.6.6 (not 5.5.7), at least in MySQL, and - second, the values OFF / ON in the Maria documentation are reversed. Apologies if this is not the correct list to raise the issue. Pantelis Theodosiou

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[Maria-discuss] New Question: Multi Master Replication and Skip Error
by AskMonty KB 08 May '15

08 May '15

Hello, A new question has been asked in "MariaDB Community" by markwass. Please answer it at http://mariadb.com/kb/en/multi-master-replication-and-skip-error/ as the person asking the question may not be subscribed to the mailing list. -------------------------------- Hi Guys I have 3 MariaDB 10 servers all running on Ubuntu 14.04 in a multi master replication setup. I had an issue the other day with replication where one of my slaves was asking me to run "SET GLOBAL sql_slave_skip_counter=1; start slave;" After running the command it did not fix the issue. So I tried "stop all slaves; SET GLOBAL sql_slave_skip_counter=1; start all slaves;" and still the issue was there. I'm wondering if it's because I'm using GlobaI Transaction ID's? Using_Gtid: Slave_Pos If this is the case then can some one explain to me how I would over come this replication error while using Global Transaction ID's? Thanks -------------------------------- To view or answer this question please visit: http://mariadb.com/kb/en/multi-master-replication-and-skip-error/

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Re: [Maria-discuss] fsync necessary for synchronous page flush?
by Xiaofei Du 07 May '15

07 May '15

Hi Jan, The only place fsync is called after AIO that I could find is in function buf_LRU_remove_pages (buf0lru.cc) But after other AIO operations, I didn't see fsync is called. Do you know how this difference will affect the recovery process? Thanks. Xiaofei On Wed, May 6, 2015 at 8:24 PM, Jan Lindström <jan.lindstrom(a)mariadb.com> wrote: > Hi, > > There is sync for AIO pages also. There is no dirty page table but > naturally dirty pages are marked and they are on LRU list see > buf/buf0lru.cc. > > R: Jan > > On Thu, May 7, 2015 at 12:23 AM, Xiaofei Du <xiaofei.du008(a)gmail.com> > wrote: > >> Hi Jan, >> >> Thanks for clarification. I should have used synchronous write, instead >> of synchronous flush. My point is that I noticed for sync writes, fsync is >> called to force pages to be on persistent storage. while for AIO pages, >> fsync is not called to force pages to be on persistent storage. My question >> here is why fsync is required for sync IOs. Does InnoDB maintain a dirty >> page table? Is fsync called to guarantee the page to be on persistent >> storage so that the dirty page table can be updated? If this is the case, >> when is the dirty page table updated for asynchronous IOs? >> >> P.S. I couldn't find code for dirty page table. So I am not sure if >> InnoDB maintains a dirty page table for recovery. Could you please give me >> a pointer to related code and related resources? Thanks. >> >> Xiaofei >> >> On Wed, May 6, 2015 at 10:12 AM, Jan Lindström <jan.lindstrom(a)mariadb.com >> > wrote: >> >>> Hi, >>> >>> Terminology is little bit confusing here. Page flushing means that we >>> have done synchronous write to disk but that does not mean that write is >>> physically on device yet, therefore there is flush to force it to >>> persistent storage. >>> >>> R: Jan >>> >>> On Wed, May 6, 2015 at 12:57 AM, Xiaofei Du <xiaofei.du008(a)gmail.com> >>> wrote: >>> >>>> Hello, >>>> >>>> When a dirty page is flushed synchronously in buf_flush_write_block_low >>>> , >>>> fsync is called in the following snippet. I am wondering why >>>> we need this fsync for synchronous flush? The record should be in >>>> the log already, so recovery should be able to successfully redo it >>>> and apply to the disk during recovery. Maybe I am missing something >>>> here, >>>> please let me know if I am wrong. Thanks much! >>>> >>>> Xiaofei >>>> >>>> >>>> /* When doing single page flushing the IO is done synchronously and we >>>> flush the changes to disk only for the tablespace we are working on. */ if >>>> (sync) { ut_ad(flush_type == BUF_FLUSH_SINGLE_PAGE); fil_flush(buf_page_get_space(bpage)); >>>> /* true means we want to evict this page from the LRU list as well. */ >>>> buf_page_io_complete(bpage, true); } >>>> >>>> _______________________________________________ >>>> Mailing list: https://launchpad.net/~maria-discuss >>>> Post to : maria-discuss(a)lists.launchpad.net >>>> Unsubscribe : https://launchpad.net/~maria-discuss >>>> More help : https://help.launchpad.net/ListHelp >>>> >>>> >>> >> >

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[Maria-discuss] fsync necessary for synchronous page flush?
by Xiaofei Du 05 May '15

05 May '15

Hello, When a dirty page is flushed synchronously in buf_flush_write_block_low, fsync is called in the following snippet. I am wondering why we need this fsync for synchronous flush? The record should be in the log already, so recovery should be able to successfully redo it and apply to the disk during recovery. Maybe I am missing something here, please let me know if I am wrong. Thanks much! Xiaofei /* When doing single page flushing the IO is done synchronously and we flush the changes to disk only for the tablespace we are working on. */ if (sync) { ut_ad(flush_type == BUF_FLUSH_SINGLE_PAGE); fil_flush(buf_page_get_space(bpage)); /* true means we want to evict this page from the LRU list as well. */ buf_page_io_complete(bpage, true); }

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[Maria-discuss] MariaDB 10 multi-source replciation with SSL enabled
by Vadim Pestovnikov 05 May '15

05 May '15

Hi all, I am having a replication issue with MariaDB 10 using multi-source replication with SSL enabled. I have MariaDB 10 db in China, MariaDB 10 db in US and MariaDB 10 db in Europe. Each of them are getting data from other database sources such as Percona Server, AWS RDS using Tungsten replication because MariaDB 10 is not compatible with AWS RDS and Percona with GTID enabled. US and China MariaDB 10 servers are masters for Europe MariaDB. When I restore US and China MariaDB 10 data in Europe MariaDB 10 slave and start the replication, slave and masers are in sync. Then new data is coming to a masters from Tungsten, but slave doesn't get it. I don't see any errors neither from mysql-error.log or slave status. When I create fake tables and insert records everything replicates perfectly. What can be possible wrong with my setup? -- Vadim

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