eG Monitoring
 
Measures reported by VnxSPTest

The storage processor enables the administrator in serving the purpose of the following:

  • creating raid group
  • Binding luns
  • All CLI commands can be executed
  • Read/Write operations from external server to SAN

Excessive usage of or heavy I/O load on a single storage processor can cause a marked deterioration in the overall performance of the storage sub-system, as it is indicative of severe deficiencies in the load-balancing algorithm that drives the storage processors. Using the VnxSPTest test, administrators can easily monitor the current state, usage, and load on each of the storage processors on the EMC VNX storage system, quickly detect an overload condition, precisely point to the storage processor that is bearing its brunt, and promptly initiate measures to resolve the issue, so as to ensure the optimal performance of the storage system.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
State Indicates the current state of this storage processor.   A storage processor can be in the Off or in the On state.

This measure can hence report one of the values - On or Off - for a storage processor.

The numeric values that correspond to the aforesaid states are as follows:

Numeric Value Measure Value
0 Off
1 On

Note:

By default, this measure reports the above-mentioned Measure Values to indicate the status of the storage processor. The graph of this measure however, represents the processor status using the numeric equivalents - 0 or 1.
Busy Indicates percent utilization of the storage processor. Percent A value close to 100 indicates that the storage processor is being excessively utilized. If both the processors are very busy, then it indicates that the load on the storage system is high, and that adequate resources may have to be allocated to both the processors to enable them to handle the load. If only a single processor is found to be extremely busy, it is a cause for concern, as it indicates that I/O load has not been uniformly distributed between the two processors, thus imposing additional strain on a particular processor.
Idle Indicates the percentage of time for which this storage processor was idle. Percent This value varies with respect to the value of the Busy measure.

In the event of an overload/slowdown, you may want to compare the value of the Idle and Busy measures of an SP to figure out whether it has been utilized optimally or under-utilized. If the Idle measure value is greater than the value of the Busy measure, it is a clear indicator of under-utilization of a storage processor, probably caused by a poor load-balancing mechanism. You may consider fine-tuning the load balancing algorithm in such a case, to make sure that load is handled more quickly and efficiently and processing bottlenecks are cleared.

Read_requests Indicates the rate of read requests to this storage processor. Reqs/Sec Comparing the value of these measures across storage processors will clearly indicate which processor is overloaded - it could also shed light on irregularities in load balancing across the processors.
Write_requests Indicates the rate of write requests to this storage processor. Reqs/Sec
Total_io Indicates the sum of read and write request rates of this storage processor. I/O/Sec A consistent rise in the value of this measure is indicative of a steady increase in the I/O load of a storage processor. If this trend is observed only for one of the processors, it could hint at load-balancing irregularities. Further investigation is hence recommended.
Data_reads Indicates the rate at which data is read via this storage processor Blocks/Sec These measures are good indicators of the I/O processing ability of the SPs. You can also compare the value of these measures across SPs to identify which SP is the slowest when handing I/O requests. By closely tracking the value of these measures for that SP over time, you can proactively detect potential processing bottlenecks and also figure out when the slowdown occurs - when reading from or writing to the storage processor?
Data_writes Indicates the rate at which data is written via this storage processor. Blocks/Sec