LU creation and deletion on EMC Symmetrix and Symmetrix DMX
A logical unit (LU) that is exported by an EMC Symmetrix or Symmetrix DMX, meaning that the LU is visible to a host, is either a Symmetrix device or a Meta device.
Symmetrix device
- N cylinders
- 15 tracks per cylinder
- 64 logical blocks per track
- 512 bytes per logical block
- 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 Symmetrix devices. This enables the EMC Symmetrix to provide LUs that are larger than a hyper. Up to 255 hypers can be concatenated to form a single meta device. Meta devices can be created using the form meta and add dev commands from the SYMCLI. This allows an extremely large LU to be created, however, if exported to the Storwize V3700 system, only the first 1 PB is used.
Do not extend or reduce meta devices that are used for managed disks (MDisks). Reconfiguration of a meta device that is used for an MDisk causes unrecoverable data-corruption.