RE: Exchange replication
- From: "Mulnick, Al" <Al.Mulnick@xxxxxxxxxx>
- To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
- Date: Thu, 22 Jan 2004 08:35:04 -0500
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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