• Physical discs are not visible to hosts.


  • Logical volumes can be created from physical discs and they are called “hyper volume extension”.


  • 256 hypers can be created on a physical disc.


  • Every hyper has its own personality.


  • Initially any hyper is known as a standard device.


  • Minimum size of a hyper can be 8mb and maximum size is 32 GB (varies according to the micro code).


  • Standard device can be unprotected, two ways mirrored, three ways mirrored, 4 way mirrored as well as raid 5 protected.


  • Unprotected Standard device less than 5 cylinders are visible to the host which can be configured as gate keeper device.


  • Standard device is visible to host when it is mapped to front end director.


  • Once the LUN is deleted it should be unmapped.


  • Standard device can be configured to different personalities which may not be visible to host unless it is protected.


  • To set the personalities change the attributes.


  • To convert standard device to BCV device it should be an unprotected device.


  • Once standard device is configured to BCV, the BCV can become two ways mirrored.


  • An unprotected standard device with less than 5 cylinders can be configured as gate keeper device.


  • If gate keeper device is not configured, any volume can become gate keeper.


  • Without gatekeeper EMC control center and solution enabler cannot be operated by host on SYMM.


  • SYMM cannot be managed through TCP/IP stack as it is a fiber channel device.


  • It requires FC adapter and HBA.


  • Solution enabler installed in the host sends API calls through the HBA across fiber channel to gate keeper device upon receiving the API’s gate keeper allows the commands execute on SYMM

METAVOLUME: -   The larger volumes created by concatenating or striping the smaller hyper volumes.

  • The size of a Meta volume depends on the micro code.
  • 2 to 255 hyper volumes can be joined to a Meta volume.
  • All hypers joined to a Meta volume should be of same size.
  • They should follow same protection mechanism.
  • Meta volume is identified by its Meta head i.e., the first volume of the Meta volume.
  • Volumes are mapped to the host through the front end director ports.
  • The ports have some flags either disabled or enabled.


  • The following flags should be enabled
  1. C bit enabled  for common serial number to volume
  2. SCSI persistent reservations enabled for cluster environment
  3. VCM enabled
  • To change the status of port flags offline the ports of directors, once

Changed, enable the directors.




  • Create six standard devices two way protected of size 450MB
  • Create eight BCV devices of size 450MB
  • Create a device unprotected of size five cylinders
  • Map the devices
  • Mask the devices



For convenience, following device names are given through out the programme.

i)                   primary host name SUN1

ii)                backup host name SUN2

iii)              SYMM IDs  277 & 694

iv)              Fe directors  1c, 1d ,16c and 16d  port No=0

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