… the failing machines. The result: the battery-backed cache was in write-through mode instead of write-back mode, and the battery was at 33% and charging. We quickly checked a few other sick machines. Same thing — write-through, battery charging. And the battery backup unit was set to run through auto-learn cycles periodically, which…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
… sequential writes, like log flushes. A question is why to use a flash memory at all, when a battery-backed disk controller write-back cache does the same thing. PZ: First Indeed writes are slower with Flash disks… searches/s HT: Strange, primary key equality searches should work through the adaptive hash index! What is your database like? Do…
Post: Battery Learning still problem many years after
February 10, 2011 By 7 Comments
… all learn phase). You can also shift cache mode in Write Through if you do not have very long time for testing… such period of times. RAID gives an option to force write back even with no battery which will likely trash your database… cache it matters a lot for writes. This is a lot better than forcing write cache without Battery as database should not…
Post: Living with backups
November 6, 2008 By 28 Comments
… RAID configurations, the performance gains are quite clear. Now going back to flushing the data out of the cache. It happens… -v -f – mysql | ssh backup@storage-host /root/backup-tools/write_backup.sh This will read /mnt/snapshot/mysql directory at… is redirected through the pipe over SSH to a remote host where a script reads the standard input and writes the archive…
Post: MySQL 4 to MySQL 5 Upgrade performance regressions
June 6, 2007 By 8 Comments
… log writes and fsyncs per second which matches your hard drive capacity. Plus you would normally see single outstanding log write all… better to get battery backed up cache unit and make sure you set your RAID cache policy to “write back“. One of the customers I worked with indeed had battery backed up cache on their system… it just was in “write through” cache…
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
… system I’m testing this on has 256MB BBU (Battery Backed up Cache) on RAID controller so we will test two…. Let us now do the test with single thread and write-through RAID cache (as if there would not be any BBU… the impact is much less in this case compared to Write Through mode because we’re mostly limited by RAID controller capacity…
Post: Percona XtraBackup 1.6.4
December 19, 2011 By 9 Comments
…each of these releases contain. Using xtrabackup to back up older MySQL or Percona Server releases …write lock and then with the write lock), we dramatically reduce the amount of time that a write lock…STDERR. With this bug fixed, we have gone through both programs and ensured that only error messages…
Post: RAID System performance surprises
March 5, 2008 By 7 Comments
… Battery Learning and Charging Build in Battery has to pass through learning cycle every 3 months or so and this cycle… this time battery backed up cache will be disabled and system will operate with write through cache possibly slowing down write performance several times… for consistency check and patrol read but not for battery backed up cache being temporary disabled. Another thing you can do…
Post: Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks
August 17, 2012 By 17 Comments
…other nodes with competing locks are automatically rolled back and will receive a deadlock error no matter…, quite simply, is the tradeoff to multi-node writing in a synchronous replication system with optimistic locking. …and go hands-on? I will walk you through real examples on this and a lot more…
Post: Why you don't want to shard.
August 6, 2009 By 34 Comments
…. Too many writes – Either the IO system, or a slave can’t keep up with the amount of writes being sent to the server. While the IO system can be improved with a RAID 10 controller w/battery backed write… build an application that works correctly when you are rolling through an upgrade where the schema will not be the same…
