Dell EMC Metro node 7.0.1 Administrator Guide

Meta-volume performance and availability requirements

Performance is not critical for meta-volumes. The minimum performance that is allowed is 40 MB/sec and 100 4 K IOP/second.

For non-flash arrays, the physical spindles for meta-volumes should be isolated from application workloads.

The following is recommended for meta-volumes:

• Read caching must be enabled
• A hot spare meta-volume must be pre-configured in case of a catastrophic failure of the active metavolume.
• If possible, do not use devices on LUN0. Paths to LUN0 are removed and added whenever its array goes through discovery. This behavior is because LUN0 can be either a default LUN or a real LUN backed by real storage."

Availability is critical for meta-volumes. The meta-volume is essential for system recovery. The best practice is to mirror the meta-volume across two or more back-end arrays to eliminate the possibility of data loss. Choose the arrays that mirror the meta-volume so that they are not required to migrate simultaneously.

If metro node temporarily loses access to all meta-volumes, the current metadata in cache is automatically written to the meta-volumes when access is restored.

If metro node permanently loses access to both meta-volumes, it continues to operate based on the metadata in memory. Configuration changes are suspended until a new meta-volume is created.