Storage planning considerations for the capacity saving function

Review the following table for information about settings, configuration, and performance considerations when using the capacity saving function.

Category	Item	Remarks
Setting	Capacity saving setting	Determine the capacity saving function to use by using the capacity saving rate(%) that is estimated by the data reduction estimation tool or the capacity saving rate(%) obtained by making a guess.
Configuration	Volume capacity	Estimate the number of volumes and the volume capacity provided to the host. For DRD-VOL, we recommend that you create volume of smaller than 2.4 TB. When 2.4 TB or larger volume is created, the processing efficiency of the capacity saving processing and that of garbage collection are degraded due to the limitation of the cache management device capacity, and the effect of data reduction is reduced. When the number of volumes is small, the following performance might not be fully achieved; host I/O performance, post-process initial capacity saving, garbage collection performance, inline data migration performance, performance of disabling capacity saving function, LDEV format performance, LDEV removal performance, and initial copy performance. To fully achieve garbage collection and post-process initial capacity saving performance, have at least 40, 24, 20, and 12 volumes in G900, G700, G370, and G350 respectively.
	Number of parity groups	Determine the number of parity groups when designing a pool. If you consider the number of parity groups, following cases can be considered: The capacity, alone The capacity and performance For details, contact customer support.
	Cache memory capacity	Determine the cache memory capacity to be installed based on the total used DRD-VOL capacity.For details, contact customer support.
	Shared memory capacity	Determine the shared memory capacity to be installed based on the total used DRD-VOL capacity. For details, contact customer support.
Performance	Estimated performance value	Estimate the average write throughput in a customer use case and confirm that garbage data does not keep increasing with the workload. For the average write throughput, estimate the write throughput in the operation cycle (1 day to 1 week, for example). Use information output by Performance Monitor for estimation. In the case where garbage data increases constantly, the capacity saving function cannot be applied.