[Glass] High Availability in GemStone

[James Foster]

Hi Bruno,

I’d be interested in how other databases handle this problem. I imagine that they do but it seems that the control would need to extend beyond the database machine(s). The challenge is that you want to avoid a single point of failure (so have redundancy), but then need to ensure that if the primary goes down it is really down.

In the 1980s I worked for a healthcare database company that supported automatic fail-over. We had a situation where the network failed in such a way that the secondary machine lost connectivity with the primary machine and thought that the primary machine was down so it “took over.” The network failure was such that half of the clients stayed with the primary (which was still visible to part of the network) and half of the clients went with the secondary (since they could no longer see the primary). When we discovered the problem we had to bring down both systems and merge the transaction log (examining each one to detect conflicts). At that point we decided that manual intervention to validate the primary failure was better than automatic failure detection. So far, it seems that GemStone has followed a similar path.

James

On Feb 20, 2014, at 5:23 AM, BrunoBB <smalltalk at adinet.com.uy> wrote:

> Hi All,
> 
> Typically in a traditional architecture you have: aReverseProxy --
> WebApplication (java) -- Database Server.
> 
> High Availability (at DataBase) means that there is an Active-Active (or
> Active-Passive) configuration, if the DataBase server goes down then the
> other DataBase will respond to WebApplication request, and the application
> still goes on (without human intervention).
> 
> It is possible to do something like this with GLASS (free license) ?
> 
> To automtically recover from a Stone that went down. I have read Admin
> Manual at page 291 "Activate the hot standby in case of failure in the
> primary". 
> 
> Can we put this process of recover in a Script that it will be executed
> after a detecting that the primary Stone is down ?
> 
> The original idea here was to develop a Java app (not by me), but i have my
> GS application already running ok. But "High Availability" without human
> intervention is a requirement.
> 
> Regards,
> Bruno
> 
> 
> 
> --
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