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Data placement in Tiers

Question asked by Saver Ur on May 4, 2015
Latest reply on May 6, 2015 by Anahad Dhillon

I am trying to understand & design solutions for our customers on tiering support using Hitachi arrays.

As part of that, i would like to clarify few questions.

 

1. I am using external storage and created a HDT pool with tiers. I observed that none of the tiers showing driveType. Does Hitachi support tiering on external storage?

    If it is supported, how to differentiate these tiers with different driveTypes?

2. If i define a Pool with three tiers and selected T3 policy, How the data placement happens?

3. Is it possible to assign a Lowest tier with diskType as SSD? or it is only meant for SATA drive? The reason for asking this question is: HiCommand CLI output doesn't specify a tier level i.e. high, medium and low. But there is a property "tierID" and it has values like 1,2,3. I am not sure whether i can correlate it with High,Medium and Low tier level. is my assumption correct?

 

Ex. There are few HDT Pools

              1. Pool1 with tiers T1 (SSD),T2(SAS),T3(SATA).

              2. Pool2 with tiers T1(SAS),T2(SATA)   => Is this a valid pool with this configuration?

              3. Pool3 with tiers T1(SSD), T2(SAS)

              4. Pool4 with tiers T1(SAS), T2(SATA), T3 (SSD)  => Is this a valid pool with this configuration?

      Case 1:- If i choose T1/T2 as a policy, which is the best pool to select?

      Case 2:- If i choose T1 as a policy, which is the best pool?

      Case 3:- If i choose T2 as policy, which is the best pool?

      Case 4:- If i choose All as policy, which is the best pool?

 

Thank you in advance.

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