System drives

Storage Subsystem Administration Guide for Hitachi NAS Platform

Part Number

System drives (SDs) are the basic logical storage element used by the server. Storage systems use RAID controllers to aggregate multiple physical disks into SDs (also known as LUs). An SD is a logical unit made up of a group of physical disks or flash drives. The size of the SD depends on factors such as the RAID level, the number of drives, and their capacity.

Hitachi Enterprise RAID storage systems have a limit of 3 TiB for standard LUs or 4 TiB for virtualized LUs (HUVM). When using legacy storage systems, it is a common practice for system administrators to build large RAID groups (often called parity groups or volume groups) and then divide them into SDs (LUs) of 2 TiB or less. With today's large physical disks, RAID groups must be considerably larger than 2 TiB to make efficient use of space.

When you create SDs:
  • Use the Hitachi storage management application appropriate for your storage system. You cannot create SDs using NAS Manager or the NAS server command line.
  • You may need to specify storage system-specific settings in the storage management application.
For more information about the settings required and the firmware that is installed for each type of storage system, contact customer support.