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How is SAN Time measured?
Understanding Total Latency: In a FlashArray environment, total latency as seen by the host application is the sum of several components. Pure Storage breaks this down into Array Time and SAN Time to help administrators pinpoint where performance bottlenecks exist.
SAN Time Definition: SAN Time represents the latency introduced by the network infrastructure between the host (initiator) and the FlashArray (target). This includes the time spent traveling across Fibre Channel or Ethernet switches, cables, and host bus adapters (HBAs). It is calculated by taking the total round-trip time measured by the host and subtracting the time the FlashArray spent processing the I/O.
Metric Breakdown: * Array Time: The time the FlashArray takes to process the I/O once it hits the front-end ports (Option C describes internal array time).
SAN Time: The transit time for the request to reach the array and the response to return to the host (Option A).
Wait Time: In ActiveCluster environments, there is also 'Mirror Latency,' which is the time spent synchronizing data to a peer array (Option B).
Troubleshooting Value: If a user reports high latency but the FlashArray GUI shows very low Array Time, the administrator can look at the SAN Time metric. A high SAN Time indicates an issue with the fabric, such as a failing SFP, a congested switch port, or oversubscribed ISLs (Inter-Switch Links).