content_image/1011418.jpg
Figure 3-18 shows the DRP Compression I/O Amplification. 

<img src='content_image/1011418.jpg'>

Note:  Writes to already allocated space will drive the need for Garbage Collection (GC). The cost of GC depends on the amount of valid data in the extent that has not been overwritten. 

## 3.3 RACE compared to Data Reduction Pools 

RACE uses a variable input with a fixed output of the inbound data stream, all of which is inline without any post process. However, RACE has to wait intermittently or pause to see if more I/O is coming for a particular volume, as shown in Figure 3-19 on page 41. The RACE minimum block size to read from the back end is 32 KB. 

One of the benefits of RACE is that it enables at least 4 - 8 times more data through decompression hardware than DRP, for a true random workload. However, DRP Compression uses fixed input with a variable output, or the opposite of RACE. 

As shown in Figure 3-20 on page 41, the DRP maximum block size to read from the back end is 8 KB (typically 4 KB or less though). With the use of 8 KB input sizes, there is a small loss in compression ratio but a gain in lower latency when all workloads are put into the same predictable small block size. 

Host I/O that is put in these small-grained block sizes in DRP results in the following functionality: 

GLYPH<SM590000> Enables fine-grained allocation of block data 

GLYPH<SM590000> Provides the ability to free back unused capacity at a fine grain 

GLYPH<SM590000> Gives consistent, predictable performance 

GLYPH<SM590000> Optimizes performance for Flash storage 

