Consider the following points regarding the results of performance benchmarks with specific conditions: 

GLYPH<SM590000> For workloads that do not compress, performance between LZ4 and ZSTD are equal. Performance is lower for FICON compression because of data expansion. 

GLYPH<SM590000> For workloads that do compress, FICON compression is the slowest in all cases. When cache is not the bottleneck, LZ4 and ZSTD performed fairly equal. When cache is the bottleneck, the method that compresses the most efficiently provides the highest performance. However, with the older TS7700 model where the CPU overhead is a significant factor, the software-based methods (especially ZSTD) might result in poor performance. 

GLYPH<SM590000> ZSTD results in lower performance with less job concurrency because of the overhead that the ZSTD algorithm incurs. A single stream LZ4/FICON can run up to two times faster than a single stream ZSTD workload. 

GLYPH<SM590000> For batch periods where few active devices run in parallel, the use of LZ4 is ideal if performance is most important. If compression is more important, ZSTD is a better choice. It is also feasible to mix workloads so that some use LZ4 while others use ZSTD. 

GLYPH<SM590000> When many workloads are expected to run in parallel, ZSTD often is the best choice for cumulative performance and compression. If some of the workloads require higher performance among others, they can choose LZ4 so that they can run independently faster, but with less compression. 

Note:  All of these comparisons are relative to the maximum achievable throughput in the configuration. Small drawer configurations can also produce results where lower job counts run faster with ZSTD because the improved compression puts less strain on the limited disk cache. 

For more information about results of performance benchmark by different compression methods, see IBM TS7700 R4.1.2 Performance , WP102751. 

## 12.3.9 Internal SSD/HDD drives for TS7700 engine 

For TS7770 Server model (3957-VED), SSD drives now are an option at the initial configuration for the server, and SAS HDD drives that were an option for previous models. With SSD drives, it leads to improved code load times, response times, and Db2 in TS7700 maintenance times. 

## 12.4 TS7700 throughput: Host I/O increments 

In a TS7700, the read/write throughput from the Host is limited by the total number of Host I/O increment features that are installed. 

The following Host I/O increment features are available: 

GLYPH<SM590000> FC 5268 100 MBps increment 

GLYPH<SM590000> FC 9268 Plant installation of 100 MBps throughput 

At least one FC 9268 (default feature) is installed. This installation can be from 1 default increment (100 MBps uncompressed data) up to 40 increments (unlimited) by adding FC 5268. A TS7760 with an 8 Gb FICON adapter installed is limited to 25 increments. 

