"GNocent" <GNocent@discussions.microsoft.com> wrote in message
news:6B80A88E-B34B-4E68-A416-F2659358D425@microsoft.com...
> Hi,
>
> What you need seems to be a "geo cluster" : you have 2 rooms, each one has
1
> server + 1 disk array (at least !).
> Geo cluster are usually constructor dependant, as microsoft cluster
services
> are only able to handle shared disk arrays (single point of failure !).
For
> that reason, some disk array vendors provide peace of software that drive
> hardware synchronous replication between the 2 disk arrays and make MSCS
> "think" that it is only volumes on a shared disk array.
> I use "SRDF/CE" ("Geospan") from EMC² (we have 2 sites with EMC² arrays on
> each site) which works fine : it monitors volume replication (srdf) and
makes
> the interaction to enable volumes on the right site when doing failovers
or
> failbacks.
> One important thing : it is only available for 32 bits windows at the
moment
> (we are waiting since Q2 2005 for the release of IA64 version *I FEEL
KINDA
> PISSED OFF*).
> Note that Geo cluster usually make hardware replication in 1 direction :
> when you failover, volumes replication is stopped, so a failback takes
longer
> time : volumes on drive arrays will have to be re-synchronized
(automatically
> on most solutions, but during this period, the resources that are moving
are
> offline !).
>
> Another solution is to acquire a third party cluster aware volume manager
> (like Veritas provides) which allows you to have the same type of
abstraction
> from the MSCS point of view, but uses different technology : writes via
the
> SAN to the volumes of both side simultaneously. It is faster for I/O
writes,
> as synchronous hardware solutions (like SRDF) waits for the acknowledge of
> the write on the replicated volume to acknowledge a write, which creates a
> small delay for each write (>=1 ms, depending of the distance and the
> activity of the arrays).
>
> The last solution i know, which is cheaper, is a "Geocluster" from NSI,
> which provides mirrored disks for MSCS, and manages the moves like the 2
> previous solutions, but uses the network for the replication ("IP
based").
> The advantage is that it allows you to make a solution without SAN or
> exepensive disk arrays. The "problem" is the performance if you have very
I/O
> consuming environments.
>
> All these solutions have a cost, and are not totally safe (MSCS quorum
> remains a single point of failure, you can have "split brain" situations,
and
> a clustered SQLServer instance can't easily run outside MSCS), and doesn't
> handle data corruption or human errors.
> So it is important to think, if you want a complete DRP, to maintain a
> "standby" instance via Log shipping, or Mirroring (2005 only), or self
made
> scripts. Ideally on a 3rd site ("ultimate drp") !
>
> (Sorry for my bad English)
>
> Guillaume.
> ====================================
> "maxzsim via SQLMonster.com" wrote:
>
> > Hi,
> >
> > I would actually want to set up 2 exactSQL SERVER on 2 different
physical
> > machine each with their own hardwares so that if one is down , the
> > application could immediately switch over to the working computer as
well as
> > part of my Diaster Recovery Procedure (DRP)
> >
> > I know that clustering works on using a SHARED DISK but that's not
offering
> > me any DRP as if the shared disk is down then nothing could work.
> >
> > actually i am quite confused with the Windows clustering and database
> > clustering , what are they actually and how can i work towards havings
my SQL
> > Server really "clustered" with DRP-awareness ?(i.e in the sense it'll
switch
> > seamlessly in event of failure of 1 server yet it can offer me DRP)
> >
> > i would have thought that log shipping offers even a better sort of
> > clustering with DRP-awareness as well as the data can be on a different
> > machine eslewhere !! although need to change the role etc ..
> >
> > appreciate ur advise
> >
> > --
> > Message posted via SQLMonster.com
> > http://www.sqlmonster.com/Uwe/Forums.aspx/sql-server-clustering/200601/1
> >