Re: multilple mysql engines, one set of shared table spaces? (addendum)
On 5/14/2014 3:45 PM, shawn l.green wrote: Hello Bruce, On 5/14/2014 2:11 PM, Bruce Ferrell wrote: OK, put away the flamethrowers, I KNOW it's dumb. I've been asked for the upteenth time is this possible and if so under what conditions? So I pose the question to the community, is it? Under what conditions? Is it reliable or not? Are there authoritative references to support the answers? Inquiring minds want to know Thanks in advance Bruce Ferrell To provide confirmation that sharing files is a 'bad idea' between any two running mysqld binaries, here are the instructions in the manual on how to have two or more mysqld instances (which can be the same program or two or more different versions of mysqld) running on your machine at the same time. Consider a shared disk as being part of the same machine as it's the files that really matter in your situation. http://dev.mysql.com/doc/refman/5.6/en/multiple-servers.html Really. I mean it. Don't do it. However, if what you want to do is have two MySQL instances setup to point to the same files from the same machine or different host machines (such as in a shared SAN disk), you can do that but only one (and I do mean exactly one) of them may be started up at a time. This is known as an Active/Passive configuration and it is one of our published HA options. http://www.mysql.com/content/download/id/284/ -- Shawn Green MySQL Senior Principal Technical Support Engineer Oracle USA, Inc. - Hardware and Software, Engineered to Work Together. Office: Blountville, TN -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
Re: multilple mysql engines, one set of shared table spaces?
Hello Bruce, On 5/14/2014 2:11 PM, Bruce Ferrell wrote: OK, put away the flamethrowers, I KNOW it's dumb. I've been asked for the upteenth time is this possible and if so under what conditions? So I pose the question to the community, is it? Under what conditions? Is it reliable or not? Are there authoritative references to support the answers? Inquiring minds want to know Thanks in advance Bruce Ferrell To provide confirmation that sharing files is a 'bad idea' between any two running mysqld binaries, here are the instructions in the manual on how to have two or more mysqld instances (which can be the same program or two or more different versions of mysqld) running on your machine at the same time. Consider a shared disk as being part of the same machine as it's the files that really matter in your situation. http://dev.mysql.com/doc/refman/5.6/en/multiple-servers.html Really. I mean it. Don't do it. -- Shawn Green MySQL Senior Principal Technical Support Engineer Oracle USA, Inc. - Hardware and Software, Engineered to Work Together. Office: Blountville, TN -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
Re: multilple mysql engines, one set of shared table spaces?
As far as I know, the only way this is possible is if your entire database is formatted as MyISAM. In that case, multiple MySQL processes, each started with external-locking enabled, may safely share a data folder. The contention will almost certainly kill you as far as performance goes.. and if you are thinking of trying this using NFS mounted files or Samba, all bets are off as file locks can/will/do NOT work leading to inevitable bad race conditions.. You might explore this for some details. http://dev.mysql.com/doc/refman/5.0/en/external-locking.html In short, it's a bad, bad idea. On Wed, May 14, 2014 at 2:11 PM, Bruce Ferrell wrote: > OK, put away the flamethrowers, I KNOW it's dumb. > > I've been asked for the upteenth time is this possible and if so under what > conditions? > > So I pose the question to the community, is it? Under what conditions? Is > it reliable or not? > > Are there authoritative references to support the answers? > > Inquiring minds want to know > > Thanks in advance > > Bruce Ferrell > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe:http://lists.mysql.com/mysql > -- - michael dykman - mdyk...@gmail.com May the Source be with you. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
