Use the following procedure to identify and remedy memory hardware bottlenecks on Oracle ZFS Storage Appliance. Based on the results of the analytic dataset, suggested corrective actions are provided to increase memory performance by installing more DRAM.
- Create a worksheet as described in Creating a Worksheet (CLI), select that worksheet, and then enter
hostname:analytics worksheets> select worksheet-000 hostname:analytics worksheet-000> dataset
set name=arc.accesses[hit/miss], and then enter
committo add cache ARC accesses broken down by hit/miss to your worksheet.
hostname:analytics worksheet-000 dataset (uncommitted)> set name=arc.accesses[hit/miss] name = arc.accesses[hit/miss] hostname:analytics worksheet-000 dataset (uncommitted)> commit
done, and then enter
doneagain to exit the context.
hostname:analytics worksheet-000> done hostname:analytics worksheets> done
- Wait at least 10 minutes, and then go to
Note:Ten minutes is a general guideline. The amount of time may be adjusted if you have shorter-duration workloads that are memory intensive.
hostname:> analytics datasets
showto view a list of available datasets.
hostname:analytics datasets> show Datasets: DATASET STATE INCORE ONDISK NAME dataset-000 active 1.27M 15.5M arc.accesses[hit/miss] dataset-001 active 517K 9.21M arc.accesses[hit/miss=metadata hits][L2ARC eligibility] ... hostname:analytics datasets>
selectand the dataset with the name
In this example, dataset name
hostname:analytics datasets> select dataset-000
read 600to read the last 600 seconds, or 10 minutes, of the dataset.
hostname:analytics dataset-000> read 600
Examine the data.
You might want to install more DRAM when all of the conditions in the following table are present.
ARC access hits for data or metadata are at least 75-97% compared to misses
The ARC is providing a benefit by storing data or metadata that the applications need.
ARC access hits for data or metadata are significantly greater than prefetch hits
The majority of the ARC accesses are for real applications rather than just the prefetch mechanism.
ARC is accessed at least 10,000 times per second
Oracle ZFS Storage Appliance is hitting DRAM, which is not the typical utilization of an idle system.
Nearly all memory is consumed by the ARC, leaving very little unused memory
Oracle ZFS Storage Appliance is utilizing all of the DRAM possible for the ARC, not just serving a hot workload out of a small subset of the DRAM that is already present.