158 DS8800 Performance Monitoring and Tuning
5.1 General workload types
The correct understanding of the existing or planned workload is the key element of the entire
planning and sizing process. Understanding the workload means having the description of the
workload pattern:
Expected or existing number of IOPS
Size of the I/O requests
Read and write ratio
Random and sequential access ratio
General purpose of the application and the workload
You might also collect the following information:
Expected cache hit ratio
The number of requests serviced from cache. This number is important for read requests,
because write requests always get into the cache first. If of 1000 requests, 100 of them are
serviced from cache, you have a 10% of cache ...