Re: [SLUG] Network Real-Time Hot Filesystem Replication?

[John Ferlito <johnf@xxxxxxxxxx>]

Keeping in mind I've never done this so no idea how well it works. I'd
say a combination of

Global File System - http://sources.redhat.com/cluster/gfs/
and
Global Network Block Device - http://sourceware.org/cluster/gnbd/

should do the trick, this document explains how
http://sources.redhat.com/cluster/wiki/DRBD_Cookbook?highlight=(CategoryHowTo)

On Sat, Apr 05, 2008 at 09:52:55AM +1100, Crossfire wrote:
> I've just spent some time quickly researching this to no real satisfaction.
>
> What I'm looking for is a way to do real-time hot-replication of a whole  
> filesystem or filesystem tree over 2 nodes (and strictly 2 nodes) without 
> STOMITH[1].
>
> The scenario is I have two identical systems with local (software) RAID1.  
> They will be tethered onto their internet feed via ethernet, and can 
> optionally be tethered to each other via Gig.
>
> I want to be able to set it up so /home (and maybe other filesystems) are 
> replicated from one to the other, in both directions, in real time so they 
> can run in an all-hot redundant cluster.
>
> The environment should be mostly read-oriented, so I can live with  
> write-latent solutions as long as they handle the race/collision  
> gracefully (preferably by actually detecting and reporting it if they  
> can't avoid it).
>
> The options I've investigated so far:
>
> * Lustre (MDS requirements[2] make this not an option)
> * GlobalFS (STOMITH requirements make this not an option.  Oriented
>   towards shared media too, which I am not using)
> * tsync (Naive concurrent operation model, but otherwise viable)
> * MogileFS (not quite what I was looking for, but none the less useful).
> * OpenAFS (read-only replication only, loss of the node hosting the
>   write volume still renders the volume unwritable).
>
> Is anybody aware of any other options that I've missed?
>
> C.
>
> [1] "Shoot The Other Machine In The Head" - the ability for any node to
>     forcibly powerdown any other node believed to be malfunctioning.
> [2] Single instance MDS only, only clusterable through shared storage.
>     d'oh.
> [3] People suggesting rsync will be taken out back and shot for not
>     reading the requirements.
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-- 
John
http://www.inodes.org/