ZFS Log Device Enhancements

The following log device enhancements are available in the Solaris Express Community Edition:

• The logbias property – In SXCE build 122, you can use this property to provide a hint to ZFS about handling synchronous requests for a specific dataset. If logbias is set to latency, ZFS uses the pool's separate log devices, if any, to handle the requests at low latency. If logbias is set to throughput, ZFS does not use the pool's separate log devices. Instead, ZFS optimizes synchronous operations for global pool throughput and efficient use of resources. The default value is latency. For most configurations, the default value is recommended. Using the logbias=throughput value might improve performance for writing database files.

• Log device removal – In SXCE build 125, you can now remove a log device from a ZFS storage pool by using the zpool remove command. A single log device can be removed by specifying the device name. A mirrored log device can be removed by specifying the top-level mirror for the log. When a separate log device is removed from the system, ZIL transaction records are written to the main pool.

  Redundant top-level virtual devices are now identified with a numeric identifier. For example, in a mirrored storage pool of two disks, the top level virtual device is mirror-0.

  For more information, see Example 4–3.