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How Data ONTAP reports disk types
Data ONTAP associates a type with every disk. This type is used to determine whether a disk can be used as a matching spare or added to an aggregate. Data ONTAP reports some disk types differently than the industry standards.
When this guide refers to a disk type, it is the type used by Data ONTAP unless otherwise specified. This guide also discusses RAID disk types, which denote the role a specific disk plays for RAID. RAID disk types are not related to Data ONTAP disk types.
The following tables show how Data ONTAP disk types map to industry standard disk types for the SAS and FC-AL storage connection architectures, and for third-party storage:
SAS storage connection architecture
Data ONTAP disk type
Primary disk characteristic
Industry standard disk type
Description
BSAS
Capacity
SATA
Bridged SAS–SATA disks with added hardware to enable them to be plugged into a SAS shelf.
SAS
Performance
SAS
SATA
Capacity
SATA
Available only as internal disks for the 20xx systems.
SSD
High-performance
SSD
Solid-state disks
Disks using Storage Encryption have a Data ONTAP disk type of SAS. However, they cannot be intermixed with any other disk type, including SAS disks that are not using Storage Encryption. If any disks on a storage system use Storage Encryption, all of the disks on the storage system (and its HA partner node) must use Storage Encryption.
FC-AL storage connection architecture
Data ONTAP disk type
Primary disk characteristic
Industry standard disk type
Description
ATA
Capacity
SATA
FCAL
Performance
FC
Third-party storage
Data ONTAP disk type
Primary disk characteristic
Industry standard disk type
Description
LUN
N/A
LUN
A logical storage device backed by third-party storage and used by Data ONTAP as a disk. In this document, these LUNs are referred to as array LUNs to distinguish them from the LUNs that Data ONTAP serves to clients.
For a specific configuration, the disk types supported depend on the storage system model, the disk shelf type, and the I/O modules installed in the system. For more information about the types of disks supported by your configuration, see the System Configuration Guide at support.netapp.com.
For information about best practices for working with different types of disks, see Technical Report 3437: Storage Best Practices and Resiliency Guide.
Related Link:  
TR 3437: Storage Best Practices and Resiliency Guide

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