When to Add More Disks (BUI)

Use this procedure to determine if you need to add more disks. Note that disks can be over-utilized by making a poor choice for the RAID profile and/or ZFS record size. In this case, it may be possible to reduce existing disk utilization by moving from RAIDZ to mirrored profiles and/or matching ZFS record sizes to client I/O sizes.

In addition, if the system is configured with no read- or write-optimized flash drives, then all of the I/O operations beyond DRAM are served by disks. For better performance, consider using flash for any workload that includes random reads or synchronous writes.

1. Create a worksheet as described in Creating a Worksheet (BUI).
2. Click the add icon next to Add statistic.
3. Go to DISK > Disks > Broken down by percent utilization.
4. Right-click on the 70% range average and click By disk.
5. Wait at least 30 minutes.

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   Note -  Thirty minutes is a general guideline. If you have short-duration workloads that are bottlenecked on disk utilization, you may want to consider selecting additional disks at less than 30 minutes.

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6. Examine the graphs.

   You may want to use more disks when at least 50% of existing disks are at least 70% utilized.