RE: Exchange replication

  • From: "Zoran" <zmarjanovic@xxxxxxxx>
  • To: exchangelist@xxxxxxxxxxxxx
  • Date: Thu, 22 Jan 2004 09:29:43 -0700

Thank you a lot Al,

I have w2k3 advanced but I don't have e2k3, and e2k is not compat with
w2k3. Anyway I will probably find a hardware solution and use MSCS. Also I
hope I'll get trial version of Stanby-server from Legato and test it
thorougly. And let you all know is it realy something or rather nothing.
Also when I set my cluster I'll let you know how did I do that and present
you with my impressions (undocumented problems, strange behaviors,
fluctuations ...).

Cheers

Zoran


> I'd use the Microsoft clustering for that.  It's not fault tolerant; it's
> highly available, but it sounds like that is what you are pretty much after
> based on the solutions you're looking at.  MCS is really good at hardware
> abstraction such that if you lose a piece of hardware on one node, you get
> the benefit of a failover.  
> 
> I recommend using Windows 2003 vs. Windows 2000.  You get improvements in
> memory handling and clustering that are well worth it. 
> 
> As for the hardware you have, you have to figure out if it's on the cluster
> HCL as a solution.  Be careful not to just look at parts, but rather look at
> the whole solution for recommended/tested configurations.
> 
> MCS was designed for the situation you mentioned.  It comes with the OS and
> will work well in that situation.  From what I can tell, you have an expense
> regardless of the solution: software replication or MCS, as well as a
> learning curve either way.  For the requirements you've shared, I think that
> MCS would be a better long term bet. Especially on Windows 2003 server.
> 
> Another poster had mentioned using a NAS, SAN, or other shared disk.  You
> cannot use a NAS device that I'm aware of.  There was some promise of the
> iSCSI NAS being tested, but otherwise Microsoft hasn't supported NAS devices
> in the past for very good reasons (IMHO). There are many cluster in a box
> solutions out there from major vendors as well as small SAN products that
> can do what you're after if you're looking to do this on the cheap. EMC
> partners with Dell for example to sell a low end SAN/Clustering solution.
> HP has similar.  Etc.
> 
> Keep in mind that clustering (third party or MCS) is not a fault tolerant
> solution.  It is a highly available solution that allows you to quickly
> recover from a hardware failure.  It does not protect you against corruption
> etc.  It basically acts like a stand-alone server and then fails over when
> told or an event causes it to.  That's another advantage: you can perform
> hardware maintenance or software upgrades (hotfixes, service packs) with a
> lot less downtime because you can fail over the node and perform the
> maintenance to the passive node while clients continue to operate.  The
> trade-off?  It's a little more expensive and takes a bit more effort to
> understand and read the docs prior to deployment of initial software load
> and upgrades.  Otherwise, it works well from what I've seen.
> 
> 
> 
> Al
> -----Original Message-----
> From: Zoran [mailto:zmarjanovic@xxxxxxxx] 
> Sent: Thursday, January 22, 2004 3:09 AM
> To: [ExchangeList]
> Subject: [exchangelist] RE: Exchange replication
> 
> 
> http://www.MSExchange.org/
> 
> Thanks Al,
> 
> There is no distance. I want to do it in the same room, to have foult
> tolerance for my main location. As I don't have experience with clustering
> and we have limited budget for it, I believed that soft solution would be
> cheaper. But non of these solutions I found is well documented and local
> resellers told me it looks too good on paper to be true. I read at
> marathontecnologies site that they have a patented solution for data
> protection as well, so I thought it could be a standard option. Can you
> recommend me a good and not too expensive hardware solution? I will use 2
> ASUS 2400 servers with w2k advanced servers.
> 
> Zoran
> 
> > Interesting.  In case of hardware based solution, you would have the 
> > same requirement and be able to meet it.  The difference is where the
> > replication code runs and what you get when done.  If the code runs on
> > the hardware, then it's abstracted from the operating system and 
> > application.  This often results in a more stable implementation in my
> > experience. It also tends to have a different cost associated.
> > 
> > In either case, if there is corruption, then that will very likely be
> > replicated as well.  I mean, that's the point, isn't it?  To have an 
> > exact replica of the original?  Bifurcating the writes is a great way
> > to do this. Setting up a geo cluster may also be an option if distance
> > is a concern.
> > 
> > I'd say if disk is the only concern, then use RAID sets and a cluster
> > (MCS
> > cluster) to mitigate the risk.  The software replication products are
> really
> > for geographically separate systems in case of datacenter disaster vs.
> > hardware failure.
> > MCS would be a lot easier and it's built into the OS already. 
> > 
> > 
> > Al
> > 
> >  
> > 
> > -----Original Message-----
> > From: Zoran [mailto:zmarjanovic@xxxxxxxx]
> > Sent: Wednesday, January 21, 2004 11:13 AM
> > To: [ExchangeList]
> > Subject: [exchangelist] RE: Exchange replication
> > 
> > http://www.MSExchange.org/
> > 
> > In case of hardware clustering, I would have shared hard disk(s). If a
> > disk(s) goes down I would need time to put it back in operational 
> > state. In case of software clustering or simple volume replication, I
> > would have a fresh copy of my exchange at any moment.
> > 
> > > What is the end goal that you are trying to achieve?  I've seen 
> > > these in action in a previous job, but I'm not overly impressed with
> > > the technical abilities of the solution.  It's a software level 
> > > solution which to me discounts it before even opening the box.  For
> > > my money, I'd prefer a more hardware based solution wherever 
> > > possible such as a SAN.
> > > 
> > > 
> > > Interested to hear what you are trying to accomplish with the 
> > > solution.
> > > 
> > > al
> > > 
> > > -----Original Message-----
> > > From: Zoran [mailto:zmarjanovic@xxxxxxxx]
> > > Sent: Wednesday, January 21, 2004 7:51 AM
> > > To: [ExchangeList]
> > > Subject: [exchangelist] Exchange replication
> > > 
> > > http://www.MSExchange.org/
> > > 
> > > Hi people,
> > > 
> > > Does anyone have experience with a software that could be used for
> > > real time replication of exchange stores. I found: Double Take and Geo
> > > Cluster (too expensive for me), Veritas-volume replicator, Marathon
> > > Technologies-FT Server, Legato-Co-Standby Server. Only Legato offers
> > > tryal version, but I would be happy to get a piece of advice from smb
> who
> > used one of these.
> > > And one more question. What do you think is there any chance that 
> > > this kind of software recognise a logical error on source server and
> > > stop replication instead of copying the error to the target server?
> > > 
> > > Thanks
> > > 
> > > Zoran
> > > 
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