Re: clustering enquires
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Another 3rd party option is LifeKeeper Protection Suite for SQL Server from
SteelEye Technology. It works with SQL 7/2000 standard and enterprise
editions and soon SQL 2005. It is an alternative to MSCS and provides both
the clustering capabilities and data replication capabilities in one package
from one vendor.
The benefits of host based replication from LifeKeeper is that you don't
have the issues that Guillaume described with storage based replication.
Failover and failback is seemless with only 2-3 minutes downtime during the
actual switchover process. The replication is automatically reversed so
that while running SQL in the DR site the changes are automatically being
replicated back to the primary site. Another benefit with LifeKeeper is
that it is a resource driven cluster, which means LifeKeeper does not
require a quorum disk, which is a single point of failure in MSCS.
In addition, LifeKeeper can support Active/Active clustering, Cascading
failover between multiple nodes (tested up to 32 nodes) and N+1
configurations with multiple active nodes and a single passive node.
LifeKeeper can work in a purely replicated storage environment, a shared
storage environment, or a hybrid environment with 2-Nodes local attached to
shared storage replicating to a third node at a remote location.
--
DISCLAIMER: I am a SteelEye Engineer with years of experience implementing
HA and DR for WIndows solutions including Exchange and SQL server.
"GNocent" <GNocent@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:6B80A88E-B34B-4E68-A416-F2659358D425@xxxxxxxxxxxxxxxx
> 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
> >
.
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