PowerMax and VMAX All Flash Solutions Design (PowerMax and VMAX All Flash SRDF/Metro Operations) Flashcards
What is the main value add of SRDF/Metro?
typically high availability for an application is provided only at the host level -SRDF provides it at the storage level also
What are the two SRDF/Metro configurations?
SRDF/Metro single host
SRDF/Metro clustered host
What is SRDF/Metro single host configuration?
configuration w/ a standalone host
uses multipath software to enable parrallel read/writes to each array
How does SRDF/Metro single host work?
identity of R1 device is federated by the metro configuration insuring that the paired R2 device appears as a single virtualized device
What is SRDF/Metro clustered host configuration?
each cluster node has dedicated access to a single array
How does SRDF/Metro clustered host work?
in either case writes to the R1 and R2 devices are synchronously copied to its SRDF device mirror
What happens if conflicts occur in an SRDF/Metro clustered host configuration?
should a conflict occur between writes to paired devices the conflict will be internally involved
if a clustered host does not have direct access to the data on the array it’s connected to it can still access it through the cluster on the other side
What are the three methods SRDF/Metro uses to determine which side is available if the link is broken between the two arrays?
Device Bias
Array Witness
Virtual Witness
What is Device Bias?
uses a configuration setting of the device pair to specify which side remains available
What is Array Witness?
uses a third physical array to determine which side is accessible
What is Virtual Witness?
(vWitness)
runs a virtual appliance on an ESXi server to determine which side is accessible
When operating w/ Device Bias what is the state of the device pair?
ActiveBias
When operating w/ a Witness what is the state of the device pair?
ActiveActive
What can be used in a Array Witness configuration for redundancy?
more than just a third array
How many vWitnesses can you have?
32
