Use the following procedure to determine if you need more write log devices for the appliance.
hostname:analytics worksheets> select worksheet-000 hostname:analytics worksheet-000> dataset
hostname:analytics worksheet-000 dataset (uncommitted)> set name="io.disks[utilization=90]" name = io.disks[utilization=90] hostname:analytics worksheet-000 dataset (uncommitted)> commit
hostname:analytics worksheet-000> done hostname:analytics worksheets> done
hostname:> analytics 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] ... dataset-019 active 290K 7.80M io.disks[utilization=90] hostname:analytics datasets>
In this example, dataset name io.disks[utilization=90] corresponds to dataset-019.
hostname:analytics datasets> select dataset-019
hostname:analytics dataset-019> read 600
You may want to add more write log devices when existing devices are 90% utilized.