[xmlblaster] RE: [xmlblaster] Mirrored Masters?
Thanks Marcel. What we are looking for is nowhere near as elegant of a solution as you've outlined below. Quoting the same page as David, we are most interested in Messages which are published are sent to all masters. Because we really just want a second master node that stays in sync with the primary master. In our scenario we don't need any type of smart failover or load balancing, we want to make sure that 2 nodes are receiving and persisting the same information. In normal usage, the primary node will always receive messages. In a catastrophic situation where the primary node fails (hardware error, etc) we need to be able to switch to the secondary node that should be in sync with the primary, and manual reconfiguration is acceptable. So from your mail below, I take it that persisting at 2 nodes is not implemented yet? If not, it sounds like you recommend mirroring at the database level? Thanks, Craig -Original Message- From: owner-xmlblas...@server.xmlblaster.org [mailto:owner-xmlblas...@server.xmlblaster.org] On Behalf Of Marcel Ruff Sent: Tuesday, December 08, 2009 4:41 AM To: xmlblaster@server.xmlBlaster.org Subject: Re: [xmlblaster] Mirrored Masters? Hi David, multi master is not implemented. The I_LoadBalancer#getClusterNode() returns one node (NodeMasterInfo) which is used to forward messages to the next node, but only to one. If you need mirroring you could, depending if you need failover or load balancing, consider following: 1) Change the xmlBlaster cluster code to handle multiple masters You need to decide in this case if the multiple masters are informed in a transaction (sync) or not (async). Clients need to be coded to choose a master depending on current load or failure. - failover and load balancing 2) You could create an extended I_Queue and I_Map plugin which duplicates the data to two DBs - failover 3) You could do low-level DB mirroring (DRDB, Linux HA et al) xmlBlaster gets on startup all information to re-establish its state. In this case the mirrored xmlBlaster is started on failure of the first, clients automatically find the mirrored as the IP is change (standard HA behaviour) - failover 4) Master/Slave operation (exists already, one master with many salves) - load balancing 5) Combination of 3) and 4) should work out of the box - failover and load balancing It depends on what you want to achieve, best regards Michele Marcel David R Robison schrieb: In the discussion on clustering in the reference manual it talks about mirrored masters: /An xmlBlaster cluster allows to have more than one master server for a specific message domain. The master nodes are //mirrored instances for those messages. Published messages reach all master nodes. Subscribed messages are retrieved using a load balance algorithm. / However, the discussion says that it has not been implemented. Has any work been done on this? Any suggestions on how to achieve this? Thanks, David -- David R Robison Open Roads Consulting, Inc. 103 Watson Road, Chesapeake, VA 23320 phone: (757) 546-3401 e-mail: drrobi...@openroadsconsulting.com web: http://openroadsconsulting.com blog: http://therobe.blogspot.com book: http://www.xulonpress.com/bookstore/bookdetail.php?PB_ISBN=9781597816526 This e-mail communication (including any attachments) may contain confidential and/or privileged material intended solely for the individual or entity to which it is addressed. If you are not the intended recipient, you should immediately stop reading this message and delete it from all computers that it resides on. Any unauthorized reading, distribution, copying or other use of this communication (or its attachments) is strictly prohibited. If you have received this communication in error, please notify us immediately. -- Marcel Ruff http://www.xmlBlaster.org http://watchee.net Phone: +49 7551 309371
Re: [xmlblaster] RE: [xmlblaster] Mirrored Masters?
Craig McIlwee schrieb: Thanks Marcel. What we are looking for is nowhere near as elegant of a solution as you've outlined below. Quoting the same page as David, we are most interested in Messages which are published are sent to all masters. Because we really just want a second master node that stays in sync with the primary master. In our scenario we don't need any type of smart failover or load balancing, we want to make sure that 2 nodes are receiving and persisting the same information. In normal usage, the primary node will always receive messages. In a catastrophic situation where the primary node fails (hardware error, etc) we need to be able to switch to the secondary node that should be in sync with the primary, and manual reconfiguration is acceptable. So from your mail below, I take it that persisting at 2 nodes is not implemented yet? No this is not implemented. If not, it sounds like you recommend mirroring at the database level? Yes. And I would recommend to go from the beginning the Linux HA (bonding,DRDB,Heartbeat etc, HP-ServiceGuard ...) way, as all the failover problems will arise over time anyhow, so I suggest doing it right from beginning. regards Marcel Thanks, Craig -Original Message- From: owner-xmlblas...@server.xmlblaster.org [mailto:owner-xmlblas...@server.xmlblaster.org] On Behalf Of Marcel Ruff Sent: Tuesday, December 08, 2009 4:41 AM To: xmlblaster@server.xmlBlaster.org Subject: Re: [xmlblaster] Mirrored Masters? Hi David, multi master is not implemented. The I_LoadBalancer#getClusterNode() returns one node (NodeMasterInfo) which is used to forward messages to the next node, but only to one. If you need mirroring you could, depending if you need failover or load balancing, consider following: 1) Change the xmlBlaster cluster code to handle multiple masters You need to decide in this case if the multiple masters are informed in a transaction (sync) or not (async). Clients need to be coded to choose a master depending on current load or failure. - failover and load balancing 2) You could create an extended I_Queue and I_Map plugin which duplicates the data to two DBs - failover 3) You could do low-level DB mirroring (DRDB, Linux HA et al) xmlBlaster gets on startup all information to re-establish its state. In this case the mirrored xmlBlaster is started on failure of the first, clients automatically find the mirrored as the IP is change (standard HA behaviour) - failover 4) Master/Slave operation (exists already, one master with many salves) - load balancing 5) Combination of 3) and 4) should work out of the box - failover and load balancing It depends on what you want to achieve, best regards Michele Marcel David R Robison schrieb: In the discussion on clustering in the reference manual it talks about mirrored masters: /An xmlBlaster cluster allows to have more than one master server for a specific message domain. The master nodes are //mirrored instances for those messages. Published messages reach all master nodes. Subscribed messages are retrieved using a load balance algorithm. / However, the discussion says that it has not been implemented. Has any work been done on this? Any suggestions on how to achieve this? Thanks, David -- Marcel Ruff http://www.xmlBlaster.org http://gpsvision.biz
RE: [xmlblaster] RE: [xmlblaster] RE: [xmlblaster] Mirrored Masters?
Yes Craig, that is exactly what I meant, i.e. a plugin that would subscribe to the primary and publish to secondary. -Original Message- From: owner-xmlblas...@server.xmlblaster.org on behalf of Craig McIlwee Sent: Tue 12/8/2009 10:13 PM To: xmlblaster@server.xmlBlaster.org Subject: [xmlblaster] RE: [xmlblaster] RE: [xmlblaster] Mirrored Masters? We have considered this approach also, but not as master/slave because the slaves don't persist topics/messages, only masters do this. In this case we would have 2 masters for a domain but they won't be configured with any knowledge of each other, i.e. no cluster setup. In the primary master we would have a plugin that does have hostname, port, etc information about secondary master. The plugin will subscribe to the primary master and publish to the secondary master. I haven't fleshed out all of the details of this approach yet, but it seems like it would work. The Linux HA suggested by Marcel is unfortunately out of the question in our scenario. We have an existing Windows environment that we won't be able to rebuild on linux, we also have no experience with Linux HA. If we do go the DB replication route I imagine we will try to take advantage of PostgresSQL's Slony-I features. Craig -Original Message- From: Sanjeev Dhiman [mailto:sanje...@brickred.com] Sent: Tuesday, December 08, 2009 11:17 AM To: xmlblaster@server.xmlBlaster.org Cc: craig.mcil...@openroadsconsulting.com Subject: RE: [xmlblaster] RE: [xmlblaster] Mirrored Masters? Hi Craig, If that is the case, does it make sense for you to implement a master slave configuration since you just need the secondary to be in sync with the primary? If yes, you could just make a subscriber that subscribes to the primary node and continues to publish to the secondary. Thanks, Sanjeev -Original Message- From: owner-xmlblas...@server.xmlblaster.org [mailto:owner-xmlblas...@server.xmlblaster.org] On Behalf Of Marcel Ruff Sent: Tuesday, December 08, 2009 9:39 PM To: xmlblaster@server.xmlBlaster.org Cc: craig.mcil...@openroadsconsulting.com Subject: Re: [xmlblaster] RE: [xmlblaster] Mirrored Masters? Craig McIlwee schrieb: Thanks Marcel. What we are looking for is nowhere near as elegant of a solution as you've outlined below. Quoting the same page as David, we are most interested in Messages which are published are sent to all masters. Because we really just want a second master node that stays in sync with the primary master. In our scenario we don't need any type of smart failover or load balancing, we want to make sure that 2 nodes are receiving and persisting the same information. In normal usage, the primary node will always receive messages. In a catastrophic situation where the primary node fails (hardware error, etc) we need to be able to switch to the secondary node that should be in sync with the primary, and manual reconfiguration is acceptable. So from your mail below, I take it that persisting at 2 nodes is not implemented yet? No this is not implemented. If not, it sounds like you recommend mirroring at the database level? Yes. And I would recommend to go from the beginning the Linux HA (bonding,DRDB,Heartbeat etc, HP-ServiceGuard ...) way, as all the failover problems will arise over time anyhow, so I suggest doing it right from beginning. regards Marcel Thanks, Craig -Original Message- From: owner-xmlblas...@server.xmlblaster.org [mailto:owner-xmlblas...@server.xmlblaster.org] On Behalf Of Marcel Ruff Sent: Tuesday, December 08, 2009 4:41 AM To: xmlblaster@server.xmlBlaster.org Subject: Re: [xmlblaster] Mirrored Masters? Hi David, multi master is not implemented. The I_LoadBalancer#getClusterNode() returns one node (NodeMasterInfo) which is used to forward messages to the next node, but only to one. If you need mirroring you could, depending if you need failover or load balancing, consider following: 1) Change the xmlBlaster cluster code to handle multiple masters You need to decide in this case if the multiple masters are informed in a transaction (sync) or not (async). Clients need to be coded to choose a master depending on current load or failure. - failover and load balancing 2) You could create an extended I_Queue and I_Map plugin which duplicates the data to two DBs - failover 3) You could do low-level DB mirroring (DRDB, Linux HA et al) xmlBlaster gets on startup all information to re-establish its state. In this case the mirrored xmlBlaster is started on failure of the first, clients automatically find the mirrored as the IP is change (standard HA behaviour) - failover 4) Master/Slave operation (exists already, one master with many salves) - load balancing 5) Combination of 3) and 4) should work out of the box - failover and load balancing It depends on what you want to achieve, best regards Michele Marcel David R Robison schrieb: In the discussion
