内存备用冗余已丢失。
默认的复制方法(也有其他可用的方法)只要求在将确认通知返回给主系统之前，备用系统的内存中收到一个日志写。
The default replication method (others are available) only requires that a log write be received in memory at the standby before acknowledgement is returned to the primary.
不过，备用服务器信息将仅存储在JDBC驱动程序端的内存中。
However, the alternate server information will only be stored in memory on the JDBC driver side.
备用DRAM和可选择镜像能够提升内存的RAS。
Spare DRAM and selective mirroring provide increased memory RAS.
因此，评估备用产品或算法时，不仅仅要对它们表现出的吞吐量进行基准测试，还要测量它们对内存的影响。
So, when evaluating alternative products or algorithms, benchmark not just their apparent throughput but also their memory impact.
调查发现，平均而言，管理员分配70%的服务器的内存给虚拟机(VMs)，保留30%作为备用。
The survey found that, on average, administrators allocate 70% of a server's RAM to virtual machines (VMs), leaving 30% in reserve.
如果到主要DB 2服务器的连接失败，DB 2将从内存中检索备用服务器信息，并将使用该备用服务器信息连接到正确的DB 2服务器。
When the connection to the primary DB2 server fails, DB2 will retrieve the alternate server information from memory and will use that alternate server information to connect to the right DB2 server.
与其它备用方案相比，它的数据分解性能比较差，但是它的确可以提供较好的内存利用率和相当快的启动时间。
Its unmarshalling performance is weak compared to other alternatives, but it does give good memory utilization and a fairly fast startup time.
Cached (KB)：在MemUsed (KB)当中，当前没有使用，而是备用于将来内存分配的内存量。
Cached (KB) : of the mem used (KB), the amount of memory that is not currently being used but is immediately available for future memory allocations.
当主用数据被更新后，就会产生主备用内存数据的一致性问题。
After the primary data is updated, there will be the coherence problem of memory data between the host and the backup.
当主用数据被更新后，就会产生主备用内存数据的一致性问题。
After the primary data is updated, there will be the coherence problem of memory data between the host and the backup.
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