CODEWITHSUNDEEP
mysql
boot13
boot13

Reputation: 155

mysqldump: Got errno 12 on write

I recently started getting these messages when I run a script that has been working without any issues for years.

The command seems to do its job, and the resulting file seems complete, which just adds to the mystery.

This is on a VPS, which has limited CPU and memory, so presumably I'm hitting one of those limits, but it would be helpful to know for sure.

So I looked for a reference about mysqldump error codes, and found nothing. There are similar questions on StackOverflow, but all for different errno numbers.

Upvotes: 1

Views: 1383

Answers (1)

HoldOffHunger
HoldOffHunger

Reputation: 20881

TLDR: If you Have Memory Issues in MySQLDump, Set max_allowed_packet (also use --quick for QuickMode)

Use this parameter to prevent memory leaks and overflows: --max_allowed_packet=2M. The default value is 16M, and the max allowed value for this is 64M. If this fails, try lower values.

Full Demo Usage

nice mysqldump
-u MYUSERNAME
-pMYPASSWORD
--max_allowed_packet=2M
-h DATABASEHOST
--default-character-set=latin1
--skip-set-charset
--no-tablespaces
-N --routines
--quick
--skip-triggers
DATABASENAME > OUTPUTFILE
  • nice: Run this command with priority.
  • max_allowed_packet: This solves the problem.
  • quick: This is another attempt to reduce memory problems by doing chunking, but this will solve errno 6 (out of memory on mysql processing), and presumably not errno 12 (out of memory in linux process-handling), but I still do it to help with memory. (Yes, quick was a bad name for this parameter.)

Diagnosing Error Code 12 (and Diagnosing Any Old Error Number)

You can always find out what an exit code means by using errno(). Exit code 12 is for...

ENOMEM — 12 : Cannot allocate memory

To see what an error code is, simply run this command in linux: errno 12, or whatever the number is. To see all of the errors possible, run errno -ls.

Basically, your host is not allowing you the memory to do the backup command.

Upvotes: 1

Related Questions