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How far have you gone before in tuning your database ? be it Oracle or DB2. The efforts are never good enough and before you breathe easy the battle begins .. again and again ...
Now you can relax a bit ... With IBM Easy Tier Server functionality available with Easy Tier, you'll be able to get more work done in terms of improvement in transactions per second (TPS).
So what exactly is Easy Tier Server ?
IBM Easy Tier Server is a unified storage caching and tiering solution across AIX servers and supported direct-attached storage (DAS) flash drives. Easy Tier Server allows the most frequently accessed or “hottest” data to be placed (cached) closer to the hosts, thus overcoming the SAN latency. The Easy Tier Server core relies on DS8870 cooperating with heterogeneous hosts to make a global decision on which data to copy to the hosts’ local SSDs, for improved application response time. Therefore, DAS SSD devices play an important role in an Easy Tier Server implementation. Specializing in high I/O performance, SSD cache has the upper hand in cost per input/output operations per second (IOPS).
The Easy Tier technology has evolved over years and is now in its fifth generation. Easy Tier Server is one of several Easy Tier enhancements, introduced with the DS8000 Licensed Machine Code 7.7.10.xx.xx. Both Easy Tier and Easy Tier Server licenses, although required, are available at no cost.
Which workloads are best fit for Easy Tier Server ?
Because Easy Tier Server implements a read-only local DAS cache on the hosts, there are some particular scenarios that can take the best advantage of this feature. These are
- Real-time analytics workload
- Large content data
- Online transaction processing (OLTP) workload
- Virtual machine (VM) consolidation
- Big Data
Under the hood
The Easy Tier Server feature consists of two major components
- The Easy Tier Server coherency server
The Easy Tier Server coherency server runs in the DS8870 and manages how data is placed onto the internal flash caches on the attached hosts. Also, it integrates with Easy Tier data placement functions for the best optimization on DS8870 internal tiers (SSD, Enterprise, and Nearline). The coherency server asynchronously communicates with the hosts system (the coherency clients) and generates caching advice for each coherency client, which is based on Easy Tier placement and statistics.
- The Easy Tier Server coherency client
The Easy Tier Server coherency client runs on the host system and keeps local caches on DAS solid-state drives. The coherency client uses the Easy Tier Server protocol to establish system-aware caching that interfaces with the coherency server. An Easy Tier Server coherency client driver cooperates with the operating system to direct I/Os either to local DAS cache or to DS8870, in a transparent way to the applications.
The POWER system has a DAS attached which is used by Easy Tier Server Coherency Client Driver to create local cache. Easy Tier Server coherency clients are designed to route I/O read hits to the application host DAS, while sending read misses directly to DS8870. In the same way, the write I/Os are routed to DS8870 and cache pages related to the I/O address spaces are invalidated on the client’s local cache to keep cache coherency and data integrity. The coherency client and coherency server share statistics to ensure that the best caching decisions are made.
And the bottom line is ?
In the lab a brokerage OLTP workload was executed simulating maximum amount of read requests. In the beginning of the run the hdisks configured for the ASM DATA disk group showed maximum utilization as no caching was enabled. 60 minutes in the run, the caching was enabled on the database host running the workload. Soon after the caching was enabled, the Easy Tier Server starts migration of hot extents from DS8870 to the database host running the Easy Tier Server coherent client. Over a period, as more and more hot extents are migrated from DS8870, maximum activity was observed on cache devices and lesser activity from DS8870 storage. As more and more extents (containing required data) were cached, the read operations requests were satisfied locally thus eliminating the need to read data from storage. The effective utilization of locally cached data showed 100% improvement in the TPS observed during the test run.
Conclusion
Whether it is a latency sensitive environment, high read/write ratio applications, or a highly parallel processing system, there is an increasing need to process data quickly and Easy Tier Server can be considered for these situations.In cases where the read performance of the storage can lead to a major bottleneck to the environment, there is a high value in faster storage, and therefore, a good fit for the Easy Tier Server.
Publications and Resources
- White paper
A white paper WP102534 is available on IBM Techdocs website that provides detailed information on the testing effort.
- Redbooks
IBM System Storage DS8870: Architecture and Implementation, SG24-8085
IBM System Storage DS8000 Host Attachment and Interoperability, SG24-8887
IBM System Storage DS88870 Product Guide
IBM System Storage DS8000 Easy Tier, REDP-4667
IBM System Storage DS8000 Easy Tier Heat Map Transfer, REDP-5015
IBM System Storage DS8000: Easy Tier Application, REDP-5014
- YouTube video
http://www.youtube.com/watch?v=SLQfNoidG3I
Disclaimer
Views / thoughts expressed above are my own, not necessarily of my employer.
