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 Lenovo Storage V series
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 are all emulated
devices and have exactly 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 using the
create dev command from the EMC
Symmetrix Command Line Interface (SYMCLI). The configuration of an LU can be changed 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 in size. 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 an extremely large LU. However,
if exported to the Lenovo Storage V series 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.