Re: Anyone using LVM for backing up?

[Thomas A. McGonagle]

Hi Tim,
 We use LVM snapshots all the time. They are essentially  
instantaneous with our 90GB innodb database files.


 A command to generate the snapshot could be:
sudo /usr/sbin/lvcreate --snapshot --name mysqlsqlbackup --size 15G / 
dev/system/data01


 Please let me know if you have any questions.
-Tom

On Jun 22, 2009, at 4:41 PM, Little, Timothy wrote:


We have a 20 gig db (that includes the MYIs and MYDs and FRMs).

We are wondering how long LVM snapshots take.. in that how long might
the DB be read-locked?  Do we have to read-lock it and flush tables?

Are we talking half a second, ten-seconds, 20 minutes?

Currently, when we copy the raw files from one directory to another,  
it
takes about 20 mins and brings the DB to it's proverbial knees.   
When we

copy the files with the db server down, it takes 10 minutes or so.

Tim...

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Re: Available parallelism in MySQL community edition 5.1.34?

[Thomas A. McGonagle]

Hi Mike,
 The way we do it is installing each mysql instance from a  
precompiled binary.


 So if you had an 8 core box, and you wanted to use each of the 8  
cores, you could install a mysql binary installation and then make 7  
copies of it. We use an internal naming convention like the following:

/data01/multi_mysql/mysql_A
/data01/multi_mysql/mysql_B
/data01/multi_mysql/mysql_C
/data01/multi_mysql/mysql_D

 Create a my.cnf under each of these mysql instance directories.

 Then all you have to do is create a mysql start up script for each  
of the instances in /etc/init.d.

The startup script needs to the following three variables set.
basedir=/data01/multi_mysql/mysql_A
datadir=/data01/multi_mysql/mysql_A/data/
export MYSQL_HOME=/data01/multi_mysql/mysql_A/

 The datadir variable is contained under the rest of the mysql  
installation. I usually put the logs under

/data01/logs/mysql_A
/data01/logs/mysql_B

 This approach is very simple, and works quite well. We use it  
instead of the multi_mysql startup/my.cnf approach.


 The approach works particularly well when you have lots of IO, as  
you said you did. We use this on large raid array DAS, and it works  
great.


 If there is anything unclear about my explanation. Please do let me  
know if you have any questions. I am happy to help.

-Tom


On Jun 10, 2009, at 2:19 PM, Mike Spreitzer wrote:


If I have a computer with many cores and multiple disks, disjoint
filesystems on those disks, and enough I/O bandwidth in the machine to
keep the disks busy, can MySQL keep those disks busy if I have it  
working

on different databases at the same time?  If so, can one MySQL server
process do that, or do I need multiple server processes?  If one  
process
is enough, presumably I have to say something clever in my.cnf to  
make it

happen; what would that be?  If it can be done with multiple server
processes, can I get that from one MySQL installation (and if so,  
how) or
do I need to somehow fool my package management system (RPM on RHEL)  
into

doing multiple installations?

Thanks,
Mike Spreitzer



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