Libelle: WAN Mirroring: How to make your Disaster Recovery Architecture distance-proof

How to make your Disaster Recovery Architecture distance-proof

For true Disaster Recovery protection, it is essential to mirror critical systems over large distances between primary and backup site. Even with the low probability of a complete outage, the subsequent dramatic impacts of data loss and system (un)availability does require DR prevention measures. Specific requirements include that the application is available with current data even after a complete outage of the primary data center.

In SAP environments for example, most new implementations require Disaster Recovery as part of the architecture just the same as functionality or response times.

Only few customers rely on tape/backup restore as primary method and opt for a ‚hot standby concept‘. Why should there be different standards for new SAP implementations than for existing?

Tape backup and restore is simply not doing the job for true Disaster Protection. When designing a hot standby site, the distance between primary and secondary system is one critical aspect of the architecture. Are two rooms in the same building sufficient? Or is it required to mirror across hundreds of miles?

We always recommend the latter since we have to assume that incidents will affect complete areas. Distance in itself is more a technical and less a conceptual hurdle. Most customers agree on the notion that the further away the secondary system is from the primary, the better. Only traditional block/storage-based mirroring technologies and subsequent high investments lead to smaller and smaller distances.

While vendors try to enhance block-based mirroring with asynchronous mirroring, FibreChannel over IP or others fixes, the concept of block-replication was always designed to mirror within short distances only.

Libelle is mirroring application landscapes in Wide Area Network settings for almost a decade. Key challenges we solved is to address limited bandwidth, network latency, large distance, data integrity and more. The following table gives an overview on the key issue and how Libelle covers them with the patented BusinessShadow solution:

Problem	Consequeces	Libelle Solution
Limited Bandwidth	High ongoing fee for network pipe	• Log- and file based mirroring instead of block-replication reduces data volume drastically • Less network require- ments with data compression and parallel shipping of data packets. • Automatic resumption of the mirror even after days of network outages.
Unstable Networks	• Block-based mirror can get out of sync and eventually have to be rebuilt from scratch • Half-automated log shipping solutions with scripts require manual interventions	Automatic resumption of the mirror even after days of network outages.
Network Latency	Latency leads to literal „data jams“ with extended distances	Parallel shipping of data packets using own, optimized TCP/IP stackscover problem of latency even with large distances.

Problem

Consequeces

Libelle Solution

Limited Bandwidth

High ongoing fee for network pipe

• Log- and file based
   mirroring instead of
   block-replication
   reduces data volume
   drastically

• Less network require-
   ments with data
   compression and
   parallel shipping of
   data packets.

• Automatic resumption
   of the mirror even
   after days of network
outages.

Unstable Networks

• Block-based mirror
   can get out of sync
   and  eventually have
   to be rebuilt from
   scratch

• Half-automated log
shipping solutions
with scripts require
manual interventions

Automatic resumption
of the mirror even after
days of network outages.

Network Latency

Latency leads to literal „data jams“ with extended distances

Parallel shipping of data packets using own,
optimized TCP/IP stackscover problem of latency even with large distances.

Libelle "Option Long Distance": Cost-Effective Mirrors in WAN settings

With Libelle „Option Long Distance“, Libelle provides a special edition for Wide Area Networks to provide true distance independence between primary and secondary site. Read more about our Option Long Distance here...