Subject DRBD

Hi Group,

We are experimenting with DRBD to give us some real-time replication to spare hardware at the recommendation of our hosting provider who has worked with DRBD for some time, but who has nil experience with Firebird. In testing we've so far been unable to break the database - either at the primary end or the remote end.

DRBD is a distributed block device that allows for real-time synchronous writing to disks in multiple servers. It adds a latency cost to the write, but in theory [depending on the protocol used] once the block layer on both machines have confirmed the write has happened then you are just at the whim of the actual devices to have really written the data. There are a number of modes that DRBD works in:

Protocol A. Asynchronous replication protocol.

Protocol B. Memory synchronous (semi-synchronous) replication protocol

Protocol C. Synchronous replication protocol

I can see from a thread in 2005 [Anne's comment copied in below for some context] that Bogdan was using DRBD all the way back then, Anne echoed that redundancy at the disk level was the way to go.

There's a couple of other threads that mention DRBD, but nothing particularly informative. 

So I have three questions...

1. Does anyone know if Firebird + DRBD is a thing or am I ploughing my own furrow?

2. Can anyone suggest a way that I could try to induce database killing activity via regular client access?

3. We have a preference for Protocol B, are we mad? 

Hopefully I'm not alone, although google thinks I am.



From: "Ann W. Harrison" <aharrison@...>

Date: Wed, 01 Jun 2005 18:17:36 -0400
Subject: Re: [firebird-support] FB 1.5.x SS Redundancy

Daniel R. Jimenez wrote:
> Alexander, Adam, thank you for your suggestions. 

Another option is to push the redundancy into the disk hardware. 
InterBase included shadowing because contemporary disk systems didn't 
provide it.