some notes about solaris zfs (oracle version)

zfs_vdev_max_queue_wait is a factor used to trigger I/O starvation avoidance behavior. Used in conjunction with zfs_vdev_max_pending to track the earliest I/O that has been issued.

If more than zfs_vdev_max_queue_wait full pending queues have been issued since, this I/O is being starved. Don't accept any more I/Os. This will drain the pending queue until the starved I/O is processed.

spa_mode_global is used to define the mode in which given zpool can be initialized internally by ZFS, typically used as READ/WRITE mode.

zfs_flags are used to control the level of debugging that ZFS can use.