Standby Latency, & The Difference Between Hot, Warm, and Cold Recovery Sites

March 8, 2016 Disaster Recovery Blog, High Availability Blog Articles, Networking Blog Articles

How urgently do you need systems back up and running after an outage? Your preferred standby latency will determine what the right recovery site is for your company.

 

Three Types of Recovery Sites

Standby latency is the time between when a standby system – in other words, your target/failover site – is told to become active, and when it is actually up and running. This varies depending on the type of secondary site you consider: hot, warm, or cold.

Hot sites are actively updated asynchronously. This means that data from your main production site is replicated over a network at an interval you select (say, every few seconds or every few minutes) depending on your recovery point objective (RPO). This occurs in real time, and provides a near-mirror image of your production site on your target systems. Standby latencies for hot sites are typically only milliseconds in length, resulting in little to no downtime during failover.

Warm sites are prepared with the necessary hardware, but not your most recent version of production. This means you must restore your most recent backup to run production from a warm site. Because your data is not being consistently replicated between production and target, there is greater latency for failover, ranging from seconds to hours.

Cold sites are the cheapest recovery option, but they are also the least effective. This is because cold sites are typically just data center spaces that aren’t set up to immediately pick up production. Requiring significant IT and engineering support to be set up when you need them, cold sites result in large standby latencies. Depending on how basic your cold site is (how much hardware it has, how much software is installed, or how long it takes to restore your backup, for instance), standby latency can start at hours in length, and be much longer.

 

So Which Is It: Hot, Warm, or Cold?

When it comes to choosing the right recovery site, your RPO will be the determining factor. How much downtime can your company afford? If your production site goes offline, do you want to pick up right where you left off, or can you work from a version from several hours ago?

A hot site will be the right choice if you want a near-mirror image of production to work from. Combined with the right high availability (HA) solution, a hot site will give a seamless transition to a nearly identical setup.

Warm standby sites are a good middle ground for business functions that are non-critical. Although they do involve a bit of latency, they still get the job done for business operations that aren’t urgent.

Cold sites are better than nothing, but provide little continuity when your main systems go offline. They also require a lot of effort to get up and running when you really need them.

All in all, the secondary site that’s right for your company will depend on your business needs and objectives, and how long you can afford to wait before having things back up and running again.

 

For more information on how to establish an effective recovery site, contact us today at 317-707-3941.

 



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