Bug #101972 Doc about Configuring an I/O Capacity Maximum is not correct
Submitted: 11 Dec 2020 9:19 Modified: 8 Jan 2021 13:54
Reporter: lalit Choudhary Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.7,8.0 OS:Any
Assigned to: CPU Architecture:Any

[11 Dec 2020 9:19] lalit Choudhary 
Description:
As described in the documentation 

https://dev.mysql.com/doc/refman/8.0/en/innodb-configuring-io-capacity.html

"If you specify an innodb_io_capacity setting at startup but do not specify a value for innodb_io_capacity_max, innodb_io_capacity_max defaults to twice the value of innodb_io_capacity, with a minimum value of 2000."

I don't see the same case in my test.
my.cnf 
[mysqld]
innodb_io_capacity=150

mysql [localhost] {msandbox} ((none)) > show variables like 'innodb_io_%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| innodb_io_capacity     | 150   |
| innodb_io_capacity_max | 2000  |
+------------------------+-------+
2 rows in set (0.01 sec)

I'm expecting 300 value for innodb_io_capacity_max variable(as it mentioned in doc that "If you specify an innodb_io_capacity setting at startup but do not specify a value for innodb_io_capacity_max, innodb_io_capacity_max defaults to twice the value of innodb_io_capacity")

How to repeat:
my.cnf 
[mysqld]
innodb_io_capacity=150

restart mysqld

mysql [localhost] {msandbox} ((none)) > show variables like 'innodb_io_%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| innodb_io_capacity     | 150   |
| innodb_io_capacity_max | 2000  |
+------------------------+-------+
2 rows in set (0.01 sec)
[11 Dec 2020 9:25] MySQL Verification Team 
Hello Lalit,

Thank you for the report and feedback!

Thanks,
Umesh
[8 Jan 2021 13:54] Daniel Price 
Posted by developer:
 
Referenced text revised as follows:

"If you specify an innodb_io_capacity setting at startup but do not
specify a value for innodb_io_capacity_max, innodb_io_capacity_max
defaults to twice the value of innodb_io_capacity or 2000, whichever value
is greater."

Thank you for the bug report.