当主系统出故障时，连续日志恢复特性使一个辅助系统可用，以替代主系统。
In case the primary system fails, the continuous log restore feature makes a secondary system available to replace the primary system.
首先是无需额外处理日至文件系统——你可以快照上简单地实现日志恢复。
First no extra handling is needed for journaling file systems - you can simply do journal recovery on snapshot.
如果主系统出故障，可以将剩下的可用逻辑日志恢复到辅助系统上，然后使后者上线，担任新的主系统。
If the primary system fails, the remaining available logical logs can be restored on the second system, which can then be brought online and function as the new primary system.
在完整恢复模式或大容量日志恢复模式下，如果最近尚未备份事务日志，则请立即进行备份以免发生日志截断。
Under the full recovery model or bulk-logged recovery model, if the transaction log has not been backed up recently, backup might be what is preventing log truncation.
我们会对每个存储层重复执行该测试套件，并且会重新运行这些测试用例2次：一次是测试事务日志恢复，然后测试常规的关闭。
We repeat the test suite for each of our storage layers. Again we rerun those test cases 2 times: once to test Transaction Log recovery and then to test Regular Shutdown.
因为您可以更改日志路径位置，所以前滚恢复所需的日志可能会在不同的目录中或在不同的设备上存在。
Because you can change the log path location, the logs needed for roll-forward recovery may exist in different directories or on different devices.
虽然这些情形不常见，但是却有导致恢复日志冲突且随之损失数据的完整性的潜在危险。
Although these conditions are rare, left unchecked they have the potential to cause recovery log collision and consequent loss of data integrity.
该清单确定在同一时间内，试图拥有相关联的恢复日志的一组服务器。
This list identifies the set of servers that attempt to own the associated recovery logs at the same time.
对于恢复，重做日志是必需的。
在事务服务场景中，事务ha策略提供逻辑以确定在规定时间内是哪台服务器拥有恢复日志。
In the case of the transaction service, the transaction HA policy provides the logic to determine which servers own a recovery log at any given time.
通过还原脱机或联机备份并使用回滚操作来恢复日志，就可处理这些故障。
These failures are handled by restoring either offline or online backups and using roll-forward operations to recover the logs.
要恢复完整的备份，重播备份之后的所有事务的日志，该过程结束之后恢复就完成了。
Restore a full backup, replay the logs of all transactions since the backup, and your recovery is complete.
如果没有使用事务的高可用性，无需指定事务恢复日志目录。
If transactional high availability is not in use, no requirement exists to specify the transactions recovery log directory.
在联机恢复中，归档日志是必需的。
添加不同的服务器将阻碍主服务器收回恢复日志，且主服务器不能正确启动。
Adding a different server prevents the home server from owning its recovery logs and stops the home server from starting correctly.
这个日志对故障恢复也很有用：如果元数据服务器发生故障，它的日志就会被重放，保证元数据安全存储在磁盘上。
The journal is also useful for failure recovery: if the metadata server fails, its journal can be replayed to ensure that metadata is safely stored on disk.
使用文件锁定确保对组成恢复日志的文件的排它访问。
File locking is used to ensure exclusive access to the files that make up a recovery log.
服务器P在主机p上运行，且对其恢复日志文件持有排它文件锁定。
Server P is running on host P and holds an exclusive file lock for its own recovery log files.
故障发生后，如图3所示，数据库和协调器最后可能会重新启动并使用恢复日志和恢复规则来确保数据完整性。
After the failure, the databases and the coordinator can eventually restart and use their recovery logs and recovery rules to insure data integrity as illustrated in Figure 3.
循环日志只能支持版本恢复。
在物理恢复完成之后，数据库实例处于快速恢复模式，等待恢复逻辑日志。
After the physical restore completes, the database instance waits in fast recovery mode to restore logical logs.
在静态组服务器清单上，列出的都是在同时间试图持有恢复日志的服务器。
The list of static group servers can be thought of as the set of servers that attempts to own the recovery logs at the same time.
在检查点之间的事务被写入到一个事务日志中，并且，如果系统发生崩溃，事务将从事务日志中恢复。
Between checkpoints, transactions are written to a transaction log and, if the system crashes, transactions are recovered from the transaction log.
在恢复处理时，使用恢复日志保证数据的完整性，这一点稍后说明。
The recovery log is used insure data integrity during recovery processing, which we will illustrate later.
当ROLLFORWARD实用程序需要使用日志文件来恢复数据库时，就会检索它们。
They are retrieved when the ROLLFORWARD utility needs to use them to restore a database.
如果事务高可用性正在被使用，则必须提供恢复日志的位置，以确保服务器的恢复日志能被群中的所有应用服务器访问。
If transactional high availability is in use, the recovery log location must be provided to ensure that the recovery logs for a server are visible to all application servers in the cluster.
一旦应用暂存的逻辑日志，只要从主要服务器接收到日志记录，就可以立即恢复应用日志记录。
Once the staged logical log records are applied, it continues to resume applying the log records as soon as they are received from the primary.
添加两个服务器将导致服务器争用恢复日志，因为两个服务器都试图处理恢复。
Adding more than one server causes recovery log contention as both servers attempt to process recovery.
主日志文件建立了一个固定大小的存储空间，这是分配给恢复日志文件的。
Primary log files establish a fixed amount of storage allocated to the recovery log files.
该变更的引入可以使得寄存事务日志的机器崩溃时，能够利用事务日志的同等恢复来完善不确定的事务。
This change was introduced to enable peer recovery of transaction log to complete in-doubt transactions when the machine hosting the transaction log crashes.
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