ALR0560E The Back-end Read Response Time of array or MDisk array or MDisk name in storage system storage system name was measured to be measured value ms/op, which violated the defined critical-stress boundary value of boundary value ms/op.
Explanation
Back-end Read Response Time measures the average number of milliseconds that it took to service each read operation for arrays and MDisks. A threshold was defined on this metric, which causes the measured value to be compared to the defined boundaries for each set of performance statistics collected from the storage system.
This message indicates that a threshold boundary violation occurred. In this case, the specified array or MDisk in the storage system has a Back-end Read Response Time that is greater than or equal to the critical-stress boundary that was defined for the related threshold.
Action
The threshold violation might indicate that a performance problem exists for this array or MDisk. Either the array or MDisk is experiencing a hardware or software related problem that is causing a drop in performance, or the array or MDisk is being overloaded with too high a workload. If the workload is too high, moving some of the array or MDisk's workload to other less busy arrays or MDisks might resolve the problem.
However this threshold indication is only as good as its defined boundary values. If the specified boundary value is too low, IBM Spectrum Control might recognize many violations, even though there is really no underlying performance problem with the MDisk. In this case, increase the boundary value in the threshold definition to reduce the number of unnecessary alerts.
Due to internal cache management issues of some storage systems, it is possible that arrays or MDisks that are idle or almost idle have surprisingly large response times. Generally this is not a cause for concern, because application performance is rarely affected due to the low I/O rates. To avoid unnecessary threshold alerts for such cases, consider enabling the Back-end Read I/O Rate filter. Use this filter to ignore any violations of the Back-end Read Response Time threshold for arrays or MDisks with very low read I/O rates.