The prior blogs in this series on clustered Data ONTAP 8.3 focused on the new features that enhance nondisruptive operations and availability. The next several blogs will focus on a number of new features that contribute to the overall efficiency and manageability of clustered Data ONTAP 8.3. One of the key new features is Advanced Drive Partitioning.
Advanced drive partitioning segments physical drives into multiple partitions. A single physical drive is shared by multiple aggregates and can be accessed by two different controllers at the same time.
There are three use cases that are supported with advanced drive partitioning:
Root-data partitioning is similar for both HDDs and SSDs. Root-data partitioning is achieved by logically dividing each drive into two partitions to form separate root and data partitions. Initiators on both storage controllers can access the same drives concurrently. Each storage controller knows the block ranges on each physical drive it is allowed to access, so data integrity is maintained.
Advanced drive partitioning improves usable capacity compared to configurations with dedicated root aggregates. For certain entry configurations, usable capacity increases by up to 45% depending on the size of the drives. This also decreases the storage overhead and cost associated with using RAID-DP for the root aggregate.
Figure 2) Example of root-data partitioning for a 24-drive active/active all-flash FAS or entry FAS system.
Advanced drive partitioning for Flash Pools is a little different than root-data partitioning. With this use case a set of SSDs is shared across multiple Flash Pool aggregates to reduce the overhead due to parity and spares, thereby providing more usable capacity. Advanced drive partitioning for Flash Pool segments each drive into four pieces rather than two. Only the SSDs in the Flash Pool aggregate are partitioned, not the HDDs.
With all three uses cases, partition sizes are defined by the system and are not user configurable and you cannot convert from an unpartitioned configuration to a partitioned configuration with data in place.