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Re: Balancing and proxing

From: Roman Naumenko <roman_at_naumenko.ca>
Date: Fri, 09 Aug 2013 20:00:44 -0400

Ryan Schmidt said the following, on 09-08-13 7:12 PM:
> On Aug 9, 2013, at 15:40, "Naumenko, Roman" wrote:
>> I wanted to check if it's possible to configure subversion in
>> master-slave mode with some sort of common URL on the proxy server or
>> loadbalancer, so end users wouldn't bother with different names for
>> slave/master/readonly and geolocal names.
> You can configure any number of read-only slaves which maintain copies of the master repository with a very slight delay. The mirroring and keeping in sync would be accomplished using svnsync. To access the repositories, users would use the hostname of a mirror near to them. For read operations, they would occur on the mirror and therefore be faster than accessing the farther-away master. For write operations, you configure the mirror to proxy those requests back to the master. (Search for "write-through proxy" for more on this.) In this way the users only need to know the address of their closest mirror; they do not need to know which is the master or to know its address.
I wanted to have universal URL, which might resolve to different IP
based on location - for performance.
But more important, I'd like to have a few nodes handling writes.
>> Of course, it would be ideal if subversion nodes could just share a
>> storage, so any sort of requests from a load balancer can processed by
>> any node without need to replicate changes over network.
> If your storage is robust (i.e. a cluster filesystem, such as Xsan) and you want to run multiple Subversion servers that each have access to the same repositories on the same storage, then yes, you can do that instead.
The storage is robust enough - NetApp or possibly SAN with all
enterprise bells and whistles.

Ok, so if multiple nodes are accessing the same mount point with repos
data, will they be able to handle writes from multiple clients
correctly? Thinking out loud: yes, they should - since it's no
difference for a repository if multiple clients commiting over same
server or few distributed nodes. Or is it different when the same
process handles all requests?
Does it mean that HA and loadbalancing should be pretty easy to setup?
It should be, yet the information is almost absent about examples of
such architecture. I must be missing something here.
--Roman
Received on 2013-08-10 02:01:20 CEST

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