MySQL Bugs: #29173: confusing error message on readonly I/O devices

Bug #29173	confusing error message on readonly I/O devices
Submitted:	18 Jun 2007 10:36	Modified:	30 Aug 2007 15:05
Reporter:	Oli Sennhauser	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S4 (Feature request)
Version:	any	OS:	Any
Assigned to:	MC Brown	CPU Architecture:	Any

Description:
When mysql is run from a readonly device this error message occurs in the error log:

070618 12:31:22  mysqld started
070618 12:31:22 [Warning] Can't create test file /home/mysql/product/mysql-6.0.0/data/master.lower-test
070618 12:31:22 [Warning] Can't create test file /home/mysql/product/mysql-6.0.0/data/master.lower-test

This is ugly and confuses the customer.

How to repeat:
chmod -R a-w data
chmod u+w data/error.log

my.cnf

[client]
port          = 3307
socket        = /home/mysql/tmp/mysql-3307.sock
[mysqld]
port          = 3307
socket        = /home/mysql/tmp/mysql-3307.sock
log_output    = FILE
skip_innodb   = 1
pid-file      = /tmp/mysql-3311.pid

Suggested fix:
master.lower-test file to /tmp for example? or even get rid of this message anyway because it does not tell us anything usefull!

Thank you for a reasonable feature request. Although I am not sure there is a point in creating this file in /tmp, we should either give a more detailed error message on what is this file used for, or at least describe that clearly in the manual.

There's no point in creating it in /tmp
if it's confusing somebody, I guess, we can add a soothing paragraph to the manual

I've added a note to the documentation that this error can be safely ignored.