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: An
LU with a capacity of 64 MB or
less is ignored by the Lenovo Storage V7000.
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.
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 V7000,
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.