Remote Replication Capabilities

Not all SANs are created equal when comparing remote replication capability. It’s amazing to see all the storage vendors marketing their capabilities as if they were technology leaders, when in fact most of their offerings are feature deficient or very (sorry extremely) expensive to deploy.

 

I’ve talked with a few customers that require offsite replication for DR/business continuity. Here is their consolidated “critical requirements” wish list.

 

Asynchronous Local and Remote Replication:

 

1. Scheduled SAN based asynchronous replication over any distance using standard IP networking gear, meaning no Fibre channel to IP bridge equipment.
2. Must work over almost any link bandwidth (T1 being the most common).
3. Technology should minimize the replicated data rate by sending only block level changes.
4. Must have some bandwidth management tools to slice up link bandwidth and share it with other applications that use the remote link.
5. Must provide the capability of failing over servers to the remote site, failing back and incrementally resynchronizing the primary site with the changes.
6. Should provide the tools necessary to replicate application-consistent data sets, making application recovery a simple matter of mounting a set of consistent volumes.

Synchronous Local and Remote Replication:

 

1. SAN based synchronous replication using standard IP networking gear, meaning no Fibre Channel to IP bridge equipment.
2. Should provide seamless application server failover and failback to the remote site and back with no manual intervention and with incremental data re-synchronization.
3. If a site fails, volumes must automatically remain online at the remaining site.
4. Must work seamlessly with server and application failover software.
5. Must work seamlessly with server virtualization HA products.
6. Capable of utilizing the bandwidth to of fat pipes (parallelism).
7. Must protect against “split brains” (insures data integrity at both sites when the link between sites is down and transactions are still being processed).
8. Capability to bring a site down for maintenance without downtime.
9. Must support applications running on more than one site and replicating to each other.
10. Geographic/site awareness with I/O preferencing based on site/subnet.

When you start going down the list of SAN storage vendors, checking off those that do not meet these basic critical requirements, your options start dropping off rapidly. When you add a requirement to keep costs down, the list thins out even more. Most of the mid-range vendors only support SAN based replication using Fibre Channel, which means expensive Fibre Channel to IP bridge equipment is required on both ends of the pipe along with training and professional services to install, not to mention the outrageous software licensing costs.

Solaris 10 for X86

I’ve already downloaded the x86 version of it, and will attempt to install this Solaris 10 release on my home VMware Server.

Here are a few links you might find useful:

- What’s new in Solaris 10 http://docs.sun.com/app/docs/doc/817-0547/gghpo?a=view

- Solaris 10u5 download page http://www.sun.com/software/solaris/get.jsp#download

HP StorageWorks 4×00/6×00/8×00 Enterprise Virtual Array configuration best practices white paper

 

HP Eva 4000

 This document PDF document is really useful – Eva best practices white paper.