When to Add More Write Log Devices (CLI)

Use the following procedure to determine if you need more write log devices for the appliance.

1. Create a worksheet as described in Creating a Worksheet (CLI), select that worksheet, and then enter dataset.

   hostname:analytics worksheets> select worksheet-000
   hostname:analytics worksheet-000> dataset

2. Enter set name="io.disks[utilization=90]", and then enter commit to add disks with utilization of at least 90% to your worksheet.

   hostname:analytics worksheet-000 dataset (uncommitted)> set name="io.disks[utilization=90]"
                              name = io.disks[utilization=90]
   hostname:analytics worksheet-000 dataset (uncommitted)> commit

3. Enter done, and then enter done again to exit the context.

   hostname:analytics worksheet-000> done
   hostname:analytics worksheets> done

4. Wait at least 10 minutes, and then go to analytics datasets.

   ---

   Note -  Ten minutes is a general guideline. This amount of time may be adjusted if you have a performance-sensitive, short-duration synchronous write workload.

   ---

   hostname:> analytics datasets

5. Enter show to 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]
   ...
   dataset-019 active     290K   7.80M  io.disks[utilization=90]
   hostname:analytics datasets>

6. Enter select and the dataset with the name io.disks[utilization=90].

   In this example, dataset name io.disks[utilization=90] corresponds to dataset-019.

   hostname:analytics datasets> select dataset-019

7. Enter read 600 to read the last 600 seconds, or 10 minutes, of the dataset.

   hostname:analytics dataset-019> read 600

8. Examine the data.

   You may want to add more write log devices when existing devices are 90% utilized.