Dell Compellent SC8000 Controller - Manual (Page 11)

Optimizing an Oracle Database with Dell Compellent Automated Tiered Storage
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Oracle Databases with Dell Compellent Data Progression
Dell Compellent Data Progression is configured by assigning Storage Profiles to volumes. Storage
Profiles define the RAID level and storage tiers on which data blocks of a volume can be stored. If Data
Progression is licensed, data can be migrated between RAID levels within a tier and between tiers. If
Data Progression is not licensed and a system uses RAID 10 and RAID 5, data can be migrated up or
down within a tier but cannot be migrated between tiers.
Dell Compellent Data Progression is tightly integrated with the Dell Compellent Data Instant Replay.
Data Instant Replay creates space-efficient snapshots of data volumes. To utilize Data Progression
effectively, it is recommended to take Data Instant Replay of the volumes on a regular basis. New data
is written by default to tier 1, RAID 10 storage to provide the best write performance. Replays move to
a lower tier with RAID 5 or 6 protection levels during the next migration cycle. Over time, infrequently
accessed data blocks move to a lower storage tier and RAID level. Moving read-only data from RAID 10
to RAID 5 or RAID 6 maintains the same read performance while freeing up storage space on the higher
tier or RAID level.
Elements of an Oracle database have unique I/O characteristics. The following general guidelines can
be followed in configuring OLTP type of Oracle databases with Dell Compellent Data Progression with
SSD drives.
 Applications with the most random data requirements can gain greatest benefit from SSD drives
over hard disk drives. Typical Oracle OLTP workloads are dominated with small and random
I/O’s. Therefore Oracle OLTP type of database is a suitable candidate to deploy with SSD
drives as the top tier in a multi-tier storage infrastructure.
 Within Oracle datafiles, database objects have different IO access patterns. For example,
indexes of OLTP databases typically are more IO intensive than other database objects.
Compellent Data Progression is able to identify the frequently accessed data blocks and
automatically move these hot data blocks to the top SSD tier, while identifying and moving less
accessed data blocks to lower storage tiers for the best performance / cost optimization.
 Oracle online redo log is an IO intensive component of an Oracle database. However, the
online redo log IO operations are primarily consisted of sequential writes, which benefit little
from SSD drives. The 15K RPM SAS or Fibre Channel drives can well serve the IO requirements
of online redo logs. Therefore, it is recommended to place online redo log files on the 15K RPM
SAS or Fibre Channel storage tier only.
 Oracle archived redo log file, which is usually stored in the Flash Recovery Area, can be stored
on SATA or lower cost Fibre Channel drives with slower rotational speed. By using Compellent
Data Progression, one can control the writes to Flash Recovery Area directed to the 15K RPM
SAS or Fibre Channel storage tier, and the replays of Flash Recovery Area stored on the SATA or
lower cost Fibre Channel storage tier.
To measure the performance benefit of Dell Compellent Data Progression for Oracle databases, Dell
engineers conducted a series of benchmark stress tests with OLTP database in various tiering
configurations. The test tools, configurations and results are detailed below.
Test tools and configurations
Quest Software’s Benchmark Factory TPC-C was used in the tests. Benchmark Factory TPC-C is a load-
generating utility that simulates OLTP users and transactions on a database for a given number of