Monday, July 25, 2011

Demonstration of Hitachi Dynamic Tiering

On the latest model of the Hitachi Data Systems enterprise storage array, the Virtual Storage Platform (VSP), HDS has included the capability to dynamically tier data at a sub-LUN (page) level. Hitachi Data Systems Dynamic Tiering (HDT) is a technology that enables optimization of an HDS Dynamically Provisioned (HDP) Pool by allocating highly referenced pages to higher tiers of storage. HDT will periodically move pages up or down the tiers depending upon access patterns.

For the purpose of this exercise, we will create a multi-tiered HDP pool. Within the HDP pool, there will be two tiers, one SAS and one SATA. From this pool, we present three volumes to a Windows server and populate each of these volumes with static data. We will initially populate all three volumes with static data, filling Tier1 (SAS) first, with the remainder of data spilling over to Tier2 (SATA). We will confirm our Tier1 is filled with static data by viewing the Tier Properties. Next, we will create what we dub, “active data” with IOMeter and generate I/O to test files on each of the three volumes. After several HDT cycles, we will revisit the Tier Properties to observe the affect that HDT has on highly referenced pages.

Storage tiering is not a new concept and there are a variety of ways to tier storage. Prior to HDT, HDS provided the capability to tier at the LUN level with Tiered Storage Manager. Other ways of tiering include file archiving and virtualizing storage. However, HDT can automatically tier data at a finer granularity without the need to set up policies or classify the data.


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