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Sunbelt W2Knews™ Electronic Newsletter
The secret of those "who always seem to know" - Over 500,000 Readers!
Wed, Oct 25, 2000 (Vol. 5, #51 - Issue #225)
The Latest In High Availability
  This issue of W2Knews™ contains:
    • The Latest In High Availability
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Hi All,

I was asked to by quite a few people recently: "In a nutshell, what are the most recent developments were in High Availability?"
Well, that is simple. You'll find it below!

Warm regards,

Stu Sjouwerman (email me with feedback: [email protected])


The Latest In High Availability

This is essentially a short conceptual technology update, nothing more. I'll approach it on a 'helicopter' level and we can drill down in detail in coming newsletters.

High Avalailability is usually expressed in '9-s'. Three nines is 99.9% uptime, and over a year that is dozens of hours downtime. Four nines is more like it. This is downtime measured in hours instead of days. Five nines is the holy grail of High Availability (abbreviated as HA). A few minutes downtime per year for mission critical sites is acceptable. So, what is the state of technology?

A single, standalone server does not cut the HA mustard. You have to have redundant hardware. Microsoft has created MS Cluster Server for this (MSCS), and it does a good job at what it does, but it's still early days. Failovers can sometimes be problematic or take too long, and there is still a single point of failure, the shared SCSI controller and drive.

Windows 2000 Advanced Server and Datacenter Server take the two cluster nodes to 4, and have IP load balancing included. That builds in more redundancy, but requires a *lot* of identical hardware and thus dollars.

For cost reasons, quite a few people choose for a 2-node MSCS and buy an specific add-on product that makes MSCS into a great solution: NSI's GeoCluster. Why? First of all, you do not need identical hardware with GeoCluster. Second, you get rid of that last pesky vulnerability of just one shared drive. GeoCluster allows you to have each node its own storage! Third, failover goes *much* faster as all the data is already on the second node. Once you have gone through a four-hour Exchange fail-over you will understand why this is important. [grin]

Last but not least, GeoCluster software allows you to create MSCS clusters without the geographic limitations. It allows the two nodes of a cluster to be broken out to a tested distance of 40KM but this depends on the bandwidth and the quality of the line.

You can replicate continuously over a shared or private IP LAN, VLAN or SAN IP connection. While standard MSCS clusters servers provide protection against server or application failure, GeoCluster adds data redundancy and provides greater protection against geographic disasters.

If you want to test GeoCluster on your Microsoft Cluster Server. Check:
and fill out the QUESTIONS ABOUT GEOCLUSTER form at the bottom. One of our Reps will get in touch with you and help with the installation. If you are in Europe, we'll send you a 3.5inch CD with the product.

Warm regards,

Stu Sjouwerman