Search Results for: innodb fsync

MySQL’s INNODB_METRICS table: How much is the overhead?

Starting with MySQL 5.6 there is an INNODB_METRICS table available in INFORMATION_SCHEMA which contains some additional information than provided in the SHOW GLOBAL STATUS output – yet might be more lightweight than PERFORMANCE_SCHEMA. Too bad INNODB_METRICS was designed during the Oracle-Sun split under MySQL leadership and so it covers only InnoDB counters. I think this […]

What is innodb_support_xa?

A common misunderstanding about innodb_support_xa is that it enables user-initiated XA transactions, that is, transactions that are prepared and then committed on multiple systems, with an external transaction coordinator. This is actually not precisely what this option is for. It enables two-phase commit in InnoDB (prepare, then commit). This is necessary not only for user-initiated […]

fsyncs on software raid on FusionIO

As soon as we get couple FusionIO cards, there is question how to join them in single space for database. FusionIO does not provide any mirroring/stripping solutions and totally relies on OS tools there. So for Linux we have software RAID and LVM, I tried to followup on my post How many fsync / sec […]

How many fsync / sec FusionIO can handle

I recently was asked how many fsync / sec ( and therefore durable transactions / sec) we can get on FusionIO card. It should be easy to test, let’s take sysbench fileio benchmark and run, the next command should make it:

So that’s 9229.35 req/sec, which is pretty impressive. For comparison the same […]

Innodb Double Write

One of very interesting techniques Innodb uses is technique called “doublewrite” It means Innodb will write data twice when it performs table space writes – writes to log files are done only once. So why doublewrite is needed ? It is needed to archive data safety in case of partial page writes. Innodb does not […]

SHOW INNODB STATUS walk through

Many people asked me to publish a walk through SHOW INNODB STATUS output, showing what you can learn from SHOW INNODB STATUS output and how to use this info to improve MySQL Performance. To start with basics SHOW INNODB STATUS is command which prints out a lot of internal Innodb performance counters, statistics, information about […]