Monitoring capacity savings

You can use the management GUI to determine the capacity savings that are created by thin-provisioning, compression, and deduplication.

The system supports several methods to save storage capacity. These methods can be used separately, but when used together can provide greater capacity savings and efficiencies for the system. The system supports thin-provisioning, compression, and deduplication. With thin-provisioned volumes, the amount of capacity that can be provisioned to hosts is not limited by the physical storage capacity because the system eliminates the unused allocated capacity. A thin-provisioned volume presents a different capacity to mapped hosts than the capacity that the volume consumes in the storage pool. The system supports thin-provisioned volumes in both standard pools and data reduction pools. With thin provisioning, storage administrators can configure thin provisioned volumes that can grow into the physical capacity they need based on the storage needs of the host. This flexibility saves on the costs to manage the storage capacity for host applications. Apart from fully allocated volumes, all volume types provide capacity savings and benefits from thin-provisioning. It can be used with compression and deduplication, or it can be used by itself. Thin-provisioning is supported in both standard pools and data reduction pools. However, data reduction pools support reclaiming capacity when it is no longer needed by hosts and then can redistribute it automatically for other uses.

Unlike thin-provisioning, which removes unused capacity, compression and deduplication increases the capacity of physical storage by reducing the size of the data itself. The system supports several types of compression technologies that can be used on the system at the same time. Software-based compression is implemented when you create volumes, where compression can be enabled on the volume. With compressed volumes, data is compressed in the software then it is written to disk, saving more space. When data is read to hosts, the software decompresses the data. Compression is available through data reduction support as part of the system. If you want volumes to use compression as part of data reduction support, compressed volumes must belong to data reduction pools. Compressed volumes can also be created in standard pools, but data reduction pools support additional capacity savings functions, such as automatic redistribution of reclaimed storage. Only Lenovo Storage V5030 and Lenovo Storage V5030F systems with memory module (16 GB DIMM) support compression. If compressed volumes are configured in standard pools, you cannot create compressed volumes in data reduction pools within the same I/O group. Potential compression savings can be calculated for existing volumes in the management GUI through a built-in compression estimation tool. This tool can be used to determine the capacity savings that are possible for existing data on the system by using compression.

The system also supports deduplication. Deduplication can be configured with thin-provisioned and compressed volumes in data reduction pools for added capacity savings. Deduplication is a type of data reduction that eliminates duplicate copies of data.When you create a volume, you can specify to include deduplication with other supported capacity savings methods, like compression and thin-provisioning. Deduplicated volumes must be created in data reduction pools.You cannot include deduplicated volumes in data reduction pools and compressed volumes in standard pools within the same I/O group. The system monitors these restrictions when you are creating volumes and issues errors if these conditions are met. However, if you are creating compressed volumes in data reduction pools, deduplication can be used within the same I/O group. If you have existing volumes in standard pools, you can migrate them to data reduction pools to add deduplication to increase capacity savings for the volume.

In addition to capacity savings from these methods, data reduction pools add another benefit by reclaiming capacity and redistributing it to other uses. Reclaimable capacity is calculated as part of the physical capacity on the system. Each of these capacity savings methods requires capacity monitoring to ensure efficient capacity provisioning on the system. Capacity savings result from using these methods and establishing best practices for capacity management in your organization and actual savings is contingent on these practices. However, compression and deduplication might provide data reduction two times greater than without these methods and thin-provisioning might provide two times the data reduction. When these data reduction methods are used together, overall capacity savings are combined.

To determine capacity savings in the management GUI, complete these steps:
  1. In the management GUI, select Dashboard.
  2. Under Capacity Savings, you can view the total capacity savings that the system currently gains from using capacity savings methods. The total capacity saving is divided into thin-provisioning, compression, and deduplication savings. Click the link to view volumes that use each of these methods to save capacity. The management GUI calculates capacity savings for each of these methods. For thin-provisioning savings, all written capacity is subtracted from all the provisioned capacity on the system. Written capacity is the space that hosts write to storage before any data reduction methods are applied. Thin-provisioning savings indicates how much capacity is provisioned to hosts but is not currently used to store data from hosts. For compression savings, the system calculates savings from compressed volumes in data reduction pools. If your system supports compression in standard pools, the total compressed savings are calculated by combining the savings from both data reduction pool and from standard pools. Deduplication savings are calculated for deduplicated volumes in data reduction pools. Deduplication is not supported in standard pools.