Auto-repair on read 读取时自动修复 

Data or metadata that are found to be damaged (e.g. because the checksum does not match) at the time they’re read from a device can be salvaged in case the filesystem has another valid copy when using block group profile with redundancy (DUP, RAID1-like, RAID5/6). The correct data are returned to the user application and the damaged copy is replaced by it. When this happen a message is emitted to the system log.
在从设备读取时发现损坏的数据或元数据（例如，因为校验和不匹配）可以在使用带有冗余的块组配置文件（DUP、类似于 RAID1、RAID5/6）时得以恢复，前提是文件系统具有另一个有效副本。正确的数据将返回给用户应用程序，并将损坏的副本替换掉。当发生这种情况时，系统日志会发出一条消息。

If there are more copies of data and one of them is damaged but not read by user application then this is not detected. To verify all data and metadata copies there’s scrub that needs to be started manually, automatic repairs happens in that case.
如果数据有多个副本，其中一个损坏但未被用户应用程序读取，则不会被检测到。为了验证所有数据和元数据副本，需要手动启动一次数据校验，这种情况下会自动进行修复。