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Posted to users@tomcat.apache.org by Jürgen Link <ju...@googlemail.com> on 2011/10/27 13:41:13 UTC
how to properly configure tomcat 7 cluster with BackupManager
Hi all,
I successfully did set up a tomcat cluster (3 nodes) with session
replication, using the standard DeltaManager.
In order to allow for more nodes, I'd like to switch to BackupManager for
primary-secondary replication on a dedicated backup node.
Unfortunately, the official documentation (and various other sources out
there) simply states "For larger clusters, to use a primary-secondary
session replication where the session will only be stored at one backup
server simply setup the BackupManager".
I therefore tried to replace DeltaManager in all node's three context.xml by
BackupManager, but sessions still get replicated on all three nodes.
I also tried to configure only one node with BackupManager, but it didn't
help either.
I'm obviously missing something - can someone give a sketch of how to
configure the cluster correctly?
Cheers
Jürgen
Re: how to properly configure tomcat 7 cluster with BackupManager
Posted by Mark Thomas <ma...@apache.org>.
On 27/10/2011 14:43, markt@apache.org wrote:
> "Jürgen Link" <ju...@googlemail.com> wrote:
>
>> Hi all, I successfully did set up a tomcat cluster (3 nodes) with
>> session replication, using the standard DeltaManager.
>>
>> In order to allow for more nodes, I'd like to switch to
>> BackupManager for primary-secondary replication on a dedicated
>> backup node. Unfortunately, the official documentation (and various
>> other sources out there) simply states "For larger clusters, to use
>> a primary-secondary session replication where the session will only
>> be stored at one backup server simply setup the BackupManager". I
>> therefore tried to replace DeltaManager in all node's three
>> context.xml by BackupManager, but sessions still get replicated on
>> all three nodes. I also tried to configure only one node with
>> BackupManager, but it didn't help either.
>>
>> I'm obviously missing something - can someone give a sketch of how
>> to configure the cluster correctly?
>
> The backup manager doesn't work the way you think it does. Consider a
> four node cluster with nodes A, B, C & D. If node A has 30 primary
> sessions (more on that on a sec) then 10 of them will be backed up on
> node B, 10 on node C and 10 on node D. Sessions may be primary
> (currently being used), backup (full copy of the primary) or proxy
> (no data but knows which nodes are primary and backup). If a node
> isn't the primary or a backup it will be a proxy.
That should say "If a node isn't the primary or a backup node for a
session then it will be a proxy node."
Also, you can use the Manager app to view sessions and it will show you
primary, backup or proxy info.
> You have to use sticky sessions with the backup manager else the
> primary node for the session keeps changing and that creates a lot of
> traffic.
>
> If the primary node fails, any other node can take over since they
> all have either a backup or the proxy info.
>
> Mark
>
>
>
>
>
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Re: how to properly configure tomcat 7 cluster with BackupManager
Posted by ma...@apache.org.
"Jürgen Link" <ju...@googlemail.com> wrote:
>Hi all,
>I successfully did set up a tomcat cluster (3 nodes) with session
>replication, using the standard DeltaManager.
>
>In order to allow for more nodes, I'd like to switch to BackupManager
>for
>primary-secondary replication on a dedicated backup node.
>Unfortunately, the official documentation (and various other sources
>out
>there) simply states "For larger clusters, to use a primary-secondary
>session replication where the session will only be stored at one backup
>server simply setup the BackupManager".
>I therefore tried to replace DeltaManager in all node's three
>context.xml by
>BackupManager, but sessions still get replicated on all three nodes.
>I also tried to configure only one node with BackupManager, but it
>didn't
>help either.
>
>I'm obviously missing something - can someone give a sketch of how to
>configure the cluster correctly?
The backup manager doesn't work the way you think it does. Consider a four node cluster with nodes A, B, C & D. If node A has 30 primary sessions (more on that on a sec) then 10 of them will be backed up on node B, 10 on node C and 10 on node D. Sessions may be primary (currently being used), backup (full copy of the primary) or proxy (no data but knows which nodes are primary and backup). If a node isn't the primary or a backup it will be a proxy.
You have to use sticky sessions with the backup manager else the primary node for the session keeps changing and that creates a lot of traffic.
If the primary node fails, any other node can take over since they all have either a backup or the proxy info.
Mark
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