Hi Alex, The wiki is a WIP for the feature that is on the roadmap. This discussion should serve well when drawing out the specifics of database-ha. Please do not hesitate to weigh in when you see the [DISCUSS] thread related to 'Database-HA' on the dev@ mailing list.
On Wed, Nov 06, 2013 at 03:10:02PM +0800, Alexey Zilber wrote: > Hi Prasanna, > > That page isn't fully correct regarding MariaDB. Please see: > https://mariadb.com/kb/en/multi-source-replication/ > > Thanks, > Alex > > > On Wed, Nov 6, 2013 at 2:35 PM, Prasanna Santhanam <t...@apache.org> wrote: > > > Incidentally, this is something that is being focussed on as part of > > the upcoming release [1]. > > > > [1] https://cwiki.apache.org/confluence/x/v5YTAg > > > > On Tue, Nov 05, 2013 at 10:42:58PM +0000, Marty Sweet wrote: > > > The issue with plain MySQL replication (espically in master-master) is > > that > > > a failed query will stop replication. A good example of this is when an > > > record is added onto each master at the same time (within a second), say > > a > > > new record which gets the same primary key and replication will stop, on > > > both hosts. That then leaves a split brain situation when you have one > > > master writing its own data and another writing to itself, all with > > > identical primary keys. Absolute nightmare. This can how ever be migrated > > > with the methods the OP mentioned (I assume - but don't have experience > > of). > > > > > > I don't think file curroption is much of an issue with DRDB, but you can > > > only have one host write to it at anyone time (limitation of file system > > > used), which makes the master-slave or master-backup setup ideal when > > > coupled with HA service management software such as Pacemaker. You then > > > have the database files in both places without the dreaded MySQL > > > replication stories. > > > > > > I think the main question lyes with if the cloud admin wants a > > > simple redundant setup or a load balanced service - it may also we worth > > > writing some documentation for this to help future installations, > > although > > > they will have to be detailed. > > > > > > I have never used Percona/MariaDB, does it resolve the master-master > > issues > > > I mentioned earlier? > > > > > > Marty > > > > > > On Tuesday, November 5, 2013, Adrian Lewis wrote: > > > > > > > Seems like the Percona solution also uses Galera for their multi-master > > > > cluster. Starting to wonder whether to go MariaDB-Galera now. Tempted > > just > > > > to leave it as master slave replicated on MySQL though. Scale really > > not > > > > an issue right now. Ho hum, fun to be had if I had the time to play. > > > > > > > > Assuming no Galera (with either MySQL/Percona/MariaDB) and just using > > > > Centos version of MySQL - does anyone have any input as to whether to > > go > > > > for replicating between two hosts using DRBD vs native MySQL > > replication? > > > > I get the impression that MySQL replication is an eventually-consistent > > > > near-realtime kind of replication whereas DRBD can be set to be > > completely > > > > synchronous replication. MySQL replication just seems a lot less fiddly > > > > than using DRBD and DRBD would replicate file corruption that MySQL > > > > replication would be largely safe from. > > > > > > > > -----Original Message----- > > > > From: Patrick Miller [mailto:patrick.mil...@sungard.com<javascript:;>] > > > > Sent: 05 November 2013 21:51 > > > > To: users@cloudstack.apache.org <javascript:;> > > > > Subject: Re: Multi-master MySQL Setup > > > > > > > > Take a look at the percona [1] implementation of mysql and there > > clustered > > > > version. > > > > Round robin reads and writes supported. > > > > > > > > 1] http://www.percona.com/ > > > > > > > > Patrick > > > > > > > > > > > > On Tue, Nov 5, 2013 at 9:55 AM, Adrian Lewis > > > > <adr...@alsiconsulting.co.uk <javascript:;>>wrote: > > > > > > > > > Hi Marty/Nux!, > > > > > > > > > > Thanks for the feedback - sounds like multi-master is not a good > > thing > > > > > then! Load will likely be very small for at least the next 6 months > > > > > but I figured that it was one of those things that could be set > > easily > > > > > now (still setting up) that I might appreciate later. > > > > > > > > > > Based on both your responses, I think I'll just leave it well alone! > > > > > Need to get to grips with pacemaker/corosync anyway for other reasons > > > > > so I'll just try that with either DRBD replication or MySQL > > replication. > > > > > > > > > > Cheers, > > > > > > > > > > Adrian > > > > > > > > > > -----Original Message----- > > > > > From: Marty Sweet [mailto:msweet....@gmail.com <javascript:;>] > > > > > Sent: 05 November 2013 17:23 > > > > > To: users@cloudstack.apache.org <javascript:;> > > > > > Subject: Re: Multi-master MySQL Setup > > > > > > > > > > Others may have had more success with this but from experience of > > > > > MySQL in multi-master setups I would avoid this entirely. > > > > > > > > > > A common setup is using DRDB to provide a master/slave: > > > > > Management 1 (MySQL Master) w/ virtual IP Management 2 (MySQL Slave) > > > > > > > > > > HA IP Address (for agents/services requiring DB write) which is > > > > > assigned to the master (using Pacemaker). > > > > > > > > > > You can then send web management client to the HA IP Address as well. > > > > > > > > > > It may be worth considering if you need load balancing, depending on > > > > > your setup - what loads are you experiencing? > > > > > > > > > > Marty > > > > > > > > > > > > > > > > > > > > On Tue, Nov 5, 2013 at 5:13 PM, Adrian Lewis > > > > > <adr...@alsiconsulting.co.uk <javascript:;>>wrote: > > > > > > > > > > > Hi All, > > > > > > > > > > > > > > > > > > > > > > > > Just wondering if anyone is using a MySQL multi-master > > configuration > > > > > > with auto_increment_offset (e.g.10) and auto_increment_increment (1 > > > > > > for server 1, 2 for server 2 etc)? Does it work? Does anyone know a > > > > > > reason why it doesn't or wouldn't work? Is there anything from an > > > > > > application point of view that could/would trip up CS if > > > > > > auto_increment values are set as more than 1? > > > > > > > > > > > > > > > > > > > > > > > > Not planning on deploying multimaster just yet but if I at least > > > > > > start with an auto_increment of 10, I'd have the option of adding a > > > > > > second master later and being able to load-balance more > > effectively. > > > > > > > > > > > > > > > > > > > > > > > > Thanks in advance, > > > > > > > > > > > > > > > > > > > > > > > > Adrian > > > > > > > > > > > > > > > > > > > > > > > > -- > > Prasanna., > > > > ------------------------ > > Powered by BigRock.com > > > > -- Prasanna., ------------------------ Powered by BigRock.com
