… the original node where the transaction is committed) Galera prevents writing conflicts to these pending transactions while they are inflight in… to disk. This has no effect on standard MySQL replication from this instance, since MySQL replication is asynchronous. What about semi-sync… more latency waiting for a write to go through, and possibly some poor user experience. batch writes Instead of updating global counters…
Post: Optimizing InnoDB for creating 30,000 tables (and nothing else)
December 22, 2011 By 5 Comments
… that disables just about every way an application can write data safely to disk. This is perfect for running a test suite… data to disk. Since you could hear how much syncing to disk was going on during my test run, not syncing to disk all the… writing and syncing FRM files. If I run the same program with libeatmydata, it only takes 15-20 seconds. Clearly it’s syncing…
Post: Comparing Percona XtraDB Cluster with Semi-Sync replication Cross-WAN
June 14, 2012 By 7 Comments
… semi-sync enabled on the slave (slave was in the other colo). XtraDB Cluster 1-colo 3 nodes in one datacenter. Writes… 60 second run. I do not believe these tests were disk-bound in any way, I utilized Percona Server’s Buffer… our 32 clients with semi-sync replication. Apparently each client must wait for it’s turn writing to the binlog and waiting…
Comment: Finding your MySQL High-Availability solution – The questions
October 20, 2009 By 36 Comments
…Michael MyISAM does not sync to disk, it only writes to the OS write cache. For the data files, (.MYD) you could probably get around by mounting the partition with the sync flag at the expense of a smaller write throughput. The real problem is the…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…fileblogpercona.commanual Created_tmp_disk_tablesblogpercona.commanual Created_…Key_readsblogpercona.commanual Key_write_requestsblogpercona.commanual Key_…sync_binlogblogpercona.commanual sync_frmblogpercona.commanual sync_master_infoblogpercona.commanual sync_relay_logblogpercona.commanual sync…
Post: Tokyo Tyrant - The Extras Part I : Is it Durable?
November 10, 2009 By 5 Comments
… server several times and found that data written out to disk without calling msync was very flaky indeed. I had… calling a sync after writes ruined performance. Looking at the code you can see why calling a sync after each write can severely… a trick from Innodb: We can easily write a a script that calls a background sync every second ( i.e. like innodb…
Post: Jeremy Cole on MySQL Replication
May 27, 2006 By 12 Comments
… for sequential writes this is why sync_binlog changes things. Two logs are synced now which requires seeks which make certain disks to flush… same track we’ll be only able to do single disk write per rotation, which is about 250 for 15000 RPM drive… really affected by this if you have a lot of writes to large database size. This is one more reason why…
Post: Tokyo Tyrant - The Extras Part II : The Performance Wall
November 11, 2009 By 3 Comments
… with the sync option hitting 99% IO wait. The interesting this here is we are actually bottlenecking on writes and not… cache and when that is exhausted have to then really write to disk not the FS Cache. Now Tyrant starts to… the above sync test, when I use 256M of memory and run my test with writes going directly to disk I hit 964…
Post: Recovering Linux software RAID, RAID5 Array
August 27, 2011 By 2 Comments
…0 active sync /dev/sda3 1 8 19 1 active sync /dev/sdb3 2 8 35 2 active sync /dev/…’ == active, ‘.’ == missing) Note the Update time here. The oldest disk to fail will have earliest update time. Here …Rd66bT-qF3P-MgES-F9jK-zQ01-t0qo-qbo070 LV Write Access read/write LV Status NOT available LV Size 13….
Post: Disaster: MySQL 5.5 Flushing
September 18, 2011 By 27 Comments
… to 135550126707 Last checkpoint at 132524978607 … Pending writes: LRU 0, flush list 105, single page… age exceeds 75% sync mark, that is signal that InnoDB performs in “sync” flushing mode. …_flushing_method = keep_average”. Unfortunately on spinning disks (as in this case), Percona Server …
