Transaction Groups are the way changed blocks are grouped together and eventually written to the pool. Transaction groups are the atomic unit that <acronym>ZFS</acronym> uses to assert consistency. Each transaction group is assigned a unique 64-bit consecutive identifier. There can be up to three active transaction groups at a time, one in each of these three states: <_:itemizedlist-1/> All administrative functions, such as <link linkend="zfs-term-snapshot"><command>snapshot</command></link> are written as part of the transaction group. When a synctask is created, it is added to the currently open transaction group, and that group is advanced as quickly as possible to the syncing state to reduce the latency of administrative commands.
snapshot"><command>Snapshot</command></link>)会作为交易群组的一部份写入。当 synctask 建立之后,便会加入到目前开放的交易群组中,然后该群组会尽快的进入同步中状态来减少管理指令的延迟。