LU creation and deletion on EMC VMAX

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A logical unit (LU) that is exported by an EMC VMAX, meaning that it is visible to a host, is either a VMAX device or a Meta device.

VMAX device

Restriction: The system ignores an LU with a capacity of 64 MB or less.
VMAX device is an EMC term for an LU that is hosted by an EMC VMAX. These devices are all emulated devices and have the same characteristics. The following are the characteristics of a VMAX device:
  • N cylinders
  • 15 tracks per cylinder
  • 64 logical blocks per track
  • 512 bytes per logical block
VMAX devices can be created by using the create dev command from the EMC Symmetrix Command Line Interface (SYMCLI). The configuration of an LU can be changed by using the convert dev command from the SYMCLI. Each physical storage device in an EMC VMAX is partitioned into 1 to 128 hyper-volumes (hypers). Each hyper can be up to 16 GB. A VMAX device maps to one or more hypers, depending on how it is configured. The following configurations are examples of hyper configurations:
  • Hypers can be mirrored (2-way, 3-way, 4-way).
  • Hypers can be formed into RAID-S groups.

Meta device

Meta device is an EMC term for a concatenated chain of EMC VMAX devices. The EMC VMAX uses a meta device to provide LUs that are larger than a hyper. Up to 255 hypers can be concatenated to form a single meta device. Using the form meta and add dev commands from the SYMCLI, you can create meta devices, which produce a large LU. However, if exported to the system, only the first 1 PB are used.

Attention: Do not extend or reduce meta devices that are used for managed disks (MDisks). Reconfiguring a meta device that is used for an MDisk causes unrecoverable data corruption.