When to Add the First Write Log Device (BUI)
Use this procedure to determine if you need a first write log device for Oracle ZFS Storage Appliance. Fibre Channel and iSCSI writes are synchronous and benefit from log devices when the write cache is enabled. Be sure to thoroughly read and understand the documented implications of enabling write caching on LUNs before proceeding. For more information, see Space Management for Shares in Oracle ZFS Storage Appliance Administration Guide, Release OS8.8.x.
To determine if you need to add more than one write log device, see When to Add More Write Log Devices (BUI).