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Re: Disk mirroring across 2 systems via the Lan/Wan



On Tue, 2002-10-29 at 10:05, Ed Wilts wrote:
> On Tue, Oct 29, 2002 at 08:14:23AM -0800, jim wrote:
> > On Tue, 2002-10-29 at 05:28, spinout wrote:
> > >   I want to have 2 systems connected by a Lan/Wan, to in real time mirror some areas of the disks, is this posible and if so how is it done.
> > > 
> > >   Many thanks
> > > 
> > >   Denis Croombs
> > > 
> > In short, no.  If you think about it there is always a delay.
> > This is something that all the business guys come and ask us for as soon
> > as they start thinking about disaster recovery.
> > Time across a net is huge compared to disk speeds and the disks and
> > their connective tissues are not fast enough for us.
> > There are lots of redundant storage options this is just not one of
> > them.
> 
> Nobody asked about mirroring across the Internet.
Maybe my answer was flip.  When I originally read this I somehow read in
this is what the question was.
  There are a few high
> availability solutions out there.  My VMS data centers have all the
> data mirrored between them and I've lost an entire data center and kept
> on running.  This technology has been available for at least 10 years -
> it's been about 4 years since we split the cluster here (the data
> centers are located across the street from each other).  Sun just
> announced wide area clustering today (only 10 years behind Digital!).
Digital did some really great stuff.
> For Linux, I believe that the Global File System, from Sistina, will do
> mirroring across the WAN.  http://www.sistina.com/products_gfs.htm.  I
> believe that there are other solutions out there too.  Veritas has their
> file system and cluster software out there now and may be able to put
> this together (I haven't looked yet).
> 
> Some of these solutions may require dark fiber or other highly available
> high-speed networks.  Our VMS cluster used a pair of dedicated ATM links
> at 155mbps.
> 
> Don't expect any of the solutions to be free or cheap.  This is not
> something somebody implements in their spare time and must have been
> funded by somebody with deep pockets. There aren't too many cluster lock
> managers for Linux out there, and without one you're dead.  
> 
> > Of course maybe you shouldn't listen to me.  I'm the unemployed one.
> 
> No comment :-)
I think you made yourself very clear.
> 
>         .../Ed (who is employed implementing HA solutions)
> 
> -- 
> Ed Wilts, Mounds View, MN, USA
> mailto:ewilts ewilts org
> Member #1, Red Hat Community Ambassador Program
> 
> 
> 
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