Resolution:
Description:
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Purpose of Phase Count and Phase Interval in Space Definition.


Environment:
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AS 2.1.*
All  OS

Resolution:
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These attributes have to do with the throttlng of re-distribution of data:

When a seeder joins or leaves a space there is a need to re-distribute (or re-replicate) data between the seeders. However, in order to minimize the impact this re-distribution has on-going space operations as it is throttled as a background operatoin. This means that, for example, if you add a new seeder to the space, AS does not stop operations on the space while it re-distributes some of the data to this new seeder, but rather the new seeder will be progressively re-distributed records (in phases) over a period of time until that re-distribution completes.

In the current (2.1 and 2.0) version of AS this re-distribution happens in small 'chunks' of data (the phases), with a small pause (the interval) between the redistribution of each phase in order for the seeders to catch-up on servicing on-going client space requests (gets, puts, takes, queries, etc...).

By default, AS is tuned to minimize the impact of re-distribution on on-going operations. In most cases there is almost no extra delay incurred by on-going space operations while a re-distribution is ocurring at the expense of the re-distribution taking a longer time (it can do to 'minutes' with larger spaces) to complete.

So if you think your on-going operations are affected (higher latency) while a re-distribution is happening then you can increase the number of phases (and/or increase the interval of time between two phases),. This will slow down the re-distribution of data.

Conversely if you think re-distribution takes too long to complete you could reduce the number of phases (thereby making each phase larger) and/or reduce the interval of time between phases. At the extreme you could have just one phase, which means that the seeders will do the complete re-distribution as fast as they can, but as they will not service any other space operations during this re-distribution you will see a pause in your space operations while the re-distribution happens.

Purpose of Phase Count and Phase Interval in Space Definition.