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● Aborts — Select only this box to view only the aborts. Select this box with other boxes to view the aborts and other
statistics. Clear this box to stop viewing aborts.
● Resets — Select only this box to view only the resets. Select this box with other boxes to view the resets and other
statistics. Clear this box to stop viewing resets.
● Timeouts — Select only this box to view only the timeouts. Select this box with other boxes to view the timeouts and other
statistics. Clear this box to stop viewing timeouts.
Viewing the Back-end Errors chart
1. From the GUI main menu, click Performance.
2. In the Performance Dashboard, select the tab in which you want to display the Back-end Errors chart (or create a custom
tab).
3. Click +Add Content.
4. Click the Back-end Errors chart icon.
Back-end Latency chart
The Back-end Latency chart on the performance dashboard provides a time-based view of the back-end I/O latency. The chart
allows you to:
● View back-end latency for a selected director or all directors
● Change the view to data received only, data sent only, or both (default)
● Place the mouse over any point on the Read or Write data latency indicators to view details for a specific director
Each array type, model, and underlying hard disk drive is different. Make sure you know your array's capabilities: response time,
IOPS, and bandwidth. Having a baseline of array performance is important so you know what your specific array and it's setup is
capable of.
Keep in mind that many things affect storage array latency, such as:
● IO request size
● Read vs. write request
NOTE:
The chart displays data only for the ports in the cluster to which you are currently connected. To simultaneously
view back-end latency for another cluster, open a second browser session and connect to the second cluster.
Guidelines
● When adding metro node to an existing environment, know what your host to storage array (native) performance. Although
metro node tends to boost read intensive workloads because of additional caching, metro node can perform only as well as
this native performance.
● High latency could indicate poor storage array performance.
● High latency due to low bandwidth could indicate array saturation or back-end fabric issues.
● In a metro node Metro system, this metric represents the local storage volume write latency, and does not reflect the time
spent sending data to or receiving data from a remote cluster.
● For arrays with write-back caching, writes will generally be faster than reads. If the read data is cached by the array, then
the latency will be comparable to that of the writes.
● High latency may be present while running snapshots or clones
● Keep in mind that many things affect storage array IOPS performance, such as:
○ Underlying disk type (SSD, FC, SATA)
○ RAID type — 0, 1, 0+1, 5, 6
○ FAST VP — Fully Automated Storage Tiering across 3 distinct tiers: Flash, enterprise hard disk drives (10K and 15K rpm),
and high-capacity SATA HDDs
○ Thin/thick pools
○ Storage array cache settings and size
○ Running snapshots/clones
Monitoring the system
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