[DRBD-user] mysql crashes when I move the datafiles from its current mysql directory to drbd file system

Lars Ellenberg lars.ellenberg at linbit.com
Tue May 13 23:25:24 CEST 2014

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Tue, May 13, 2014 at 04:13:17AM -0700, ARUN CHAKRAPANI RAO wrote:
> Hi,
> I am new to this drbd configuration concept.
> I am running mysql/drbd on a ubuntu 12.04 64 bit server running on vmware.
> I am trying to move my existing mysql database to drbd file system, which is in turn replicating to another node.
> I shut down the db. edited the my.cnf file and updated the datadir to
> datadir                = /var/lib/mysql_drbd
> and
> log_bin                        = /var/lib/mysql_drbd/mysql-bin.log
> I copied all the files under the default mysql directory to this new drbd files.
> set the permissions to the new file system to chown mysql:mysql /var/lib/mysql_drbd
> started the db using service mysql start. it just crashes. but if I change the path to the original location it starts working fine.
> Please do let me know if you have faced similar kind of an issue.
> How to solve this. Is there any parameters which needs to be set in order for this db to be working on drbd file systems.
> Any help greatly appreciated.
> Attempting backtrace. You can use the following information to find out
> where mysqld died. If you see no messages after this, something went
> terribly wrong...
> stack_bottom = 0 thread_stack 0x30000
> /usr/sbin/mysqld(my_print_stacktrace+0x29)[0x7f219dfb8989]
> /usr/sbin/mysqld(handle_fatal_signal+0x483)[0x7f219de7dbd3]
> /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f219cbc7cb0]
> /usr/sbin/mysqld(_ZN9MYSQL_LOG17generate_new_nameEPcPKc+0x9b)[0x7f219df1183b]
> /usr/sbin/mysqld(_ZN13MYSQL_BIN_LOG4openEPKc13enum_log_typeS1_10cache_typebmbb+0x204)[0x7f219df15684]
> /usr/sbin/mysqld(+0x285461)[0x7f219dce4461]
> /usr/sbin/mysqld(_Z11mysqld_mainiPPc+0x624)[0x7f219dce7694]
> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed)[0x7f219c21d76d]
> /usr/sbin/mysqld(+0x27e6d5)[0x7f219dcdd6d5]

If you mysql segfaults (or whatever this is),
that has nothing to do with DRBD.
But you likely have not copied enough stuff,
or forgot to adjust a few mysql parameters,
possibly some innodb paths.

Maybe first try your procedure without DRBD,
but with two "classic" file systems / mount points first.

*then* put one of those file systems on DRBD.

You could try to keep the my.cnf as is, and simply symlink
/var/lib/mysql to where your new mount point is (after rsync'ing
everything over again, apparently right now it's a complete mess).

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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