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Re: Balancing and proxing

From: Ryan Schmidt <subversion-2012c_at_ryandesign.com>
Date: Fri, 9 Aug 2013 20:15:27 -0500

On Aug 9, 2013, at 19:00, Roman Naumenko wrote:
> Ryan Schmidt said the following, on 09-08-13 7:12 PM:
>> 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.

I'm not familiar with how to set that up at the DNS level but if you are then go for it.

> But more important, I'd like to have a few nodes handling writes.

Ah yes. Well then that's different.

You must have one heck of a large svn installation for that to be a bottleneck.

>>> 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.

It would need to be not just a SAN but a SAN with a cluster filesystem, based on previous conversations (see below).

> 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?

I have not set it up myself, but I participated in discussions about it on this list some years ago:

http://svn.haxx.se/users/archive-2006-10/0195.shtml

http://svn.haxx.se/users/archive-2007-05/0214.shtml

You may want to read those threads completely and carefully to get all the nuances. And of course information may have changed since then.
Received on 2013-08-10 03:16:22 CEST

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