Is there a "max" number of zones in Swift?

asked 2013-07-31 14:34:22 -0500

Caroline gravatar image

In a Swift cluster with 3 replicas, it is suggested that you have 3-5 zones.

As far as scale out is concerned, is there any benefit/detriment to continuing to add zones as new storage is added?

Is there a "max" number of zones you should have? If so, why?

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answered 2013-07-31 15:09:57 -0500

nosluoc gravatar image

updated 2013-07-31 16:59:17 -0500

smaffulli gravatar image

According to OpenStack's Swift Deployment Guide (, zones are 'abstract' in that you define how much separation exists between the zones in your deployment. To my knowledge, there is no limit to the number of zones you can have. It's more important to plan the number of zones according to your application: are all zones powered separately? Are they on the same switch? As far as Swift is concerned, zones are used to isolate data and to clearly define failure boundaries. You can define a zone as a single drive at the smallest level, up to multiple racks on a larger scale. This also gives Swift a sense of the health/status of the replicas, allowing it to tolerate outages of zones without losing all available replicas of data.

TL;DR - Since zones are relative to the use case, there's no definite answer to your question. A zone could be a single drive that fails, or it could be an entire cabinet. Generally speaking, if properly planned out, more zones would increase the fault tolerance of Swift.

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Thank you for converting the URL to a hyperlink. :)

nosluoc gravatar imagenosluoc ( 2013-08-01 09:40:09 -0500 )edit

Okay, so say I have 20 racks and I want each rack to be a zone.. You're saying there are no issues (that you are aware of) with having 20 zones?

Caroline gravatar imageCaroline ( 2013-08-01 10:43:09 -0500 )edit

None. It's entirely up to the admin to define the number/scope of zones.

nosluoc gravatar imagenosluoc ( 2013-08-01 12:09:07 -0500 )edit

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Asked: 2013-07-31 14:34:22 -0500

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Last updated: Jul 31 '13