You get redundancy even with two nodes, BUT - You're missing the point... Re-read your original email, notice the line saying "a NDB cluster needs at least three nodes.". Well, it doesn't *NEED* at least 3 nodes to function - the *technical* minimum is 1 physical node. The *practical* minimum is obviously 2.
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Yonah Russ Sent: Tuesday, November 20, 2007 7:26 PM To: Imri Zvik Cc: linux-il@cs.huji.ac.il Subject: Re: MySQL Cluster for HA? What about PostgresQL PGCluster? I believe the original inquiry was regarding HA - Less than three nodes does not have any HA benefits AFAIK. yonah On Nov 20, 2007 10:36 AM, Imri Zvik < [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> > wrote: Hi, The MySQL cluster can run perfectly on one physical node. The 3 nodes you're referring to are at least 1 management node, and at least 1 API ("mysqld") node, and at least 1 data/storage ("ndbd") node. They can all reside on the same physical node. The main issue with NDB version 5.0 (from my point of view) is that it must load all data into memory at runtime, so if your database is larger than your amount of RAM, you better find some other solution, or split it to enough replicas (data nodes) so that each chunk would fit. This problem is going to be solved with 5.1, but it is not even near being production-ready (at least last time I've checked). > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of > Yonah Russ > Sent: Tuesday, November 20, 2007 6:53 AM > To: Amos Shapira > Cc: linux-il@cs.huji.ac.il > Subject: Re: MySQL Cluster for HA? What about PostgresQL PGCluster? > > Hi, > > AFAIK MySQL cluster requires using the NDB engine which is not 100% > compatible with MYISAM, etc. The more recent a version you have the > better off you will be but there was one point where autoincrement > wasn't even supported. Also from what I know, a NDB cluster needs at > least three nodes. > > That doesn't mean you can't have an active-active database. If you > application is ready for it, you can set up MySQL in a Master Master > configuration (aka multimaster). For your application to be compatible > you basically need to use only autoincrement primary keys for all your > tables but you should read the whole Megilah - here is a good article: > http://www.onlamp.com/pub/a/onlamp/2006/04/20/advanced-mysql- > replication.html > > Google has also released some code for multimaster configurations and > they have some docs also: > http://code.google.com/p/mysql-master-master/ > > Regarding Postgres- I can't recommend anything specific but I am > looking into pgpool and pgpool II for a new project. > > Hope that helps, > Yonah > > > On Nov 20, 2007 2:51 AM, Amos Shapira <[EMAIL PROTECTED] > wrote: > > > Hello, > > We are looking at enhancing one of our servers, which runs CentOS > 5 on > amd64, for HA using Linux Virtual Servers (LVS). The server runs > a web > site using MySQL 5.0.22 and of course we'll need to replicate > that on > the second server as well. > > Is MySQL Cluster the right solution for us? > > At least for now, we think we can do with a master-slave solution > (i.e. only one server serving while the other is in "hot > standby"), > but if it's possible to take advantage of both servers at the > same > time and double our capacity then it would be very useful too. > > I also have a small web service using PostgresQL (8.1.9, from > CentOS > packages) on the same server which will also have to be > replicated. > What do people usually use to do this? Is PGCluster a practical > option? > > Thanks, > > --Amos > > ================================================================= > To unsubscribe, send mail to [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED] > with > the word "unsubscribe" in the message body, e.g., run the command > echo unsubscribe | mail [EMAIL PROTECTED] > > >
