恢复SQL Server 2005数据库时性能计数器的问题
今天我对 200G
的数据库进行了恢复 当恢复开始时,我在 perfmon 上看到它们仅写入磁盘
我将数据文件恢复到但没有从源(同一磁盘)读取。
以平均 100MB/秒的速度向磁盘写入30分钟后。
perfmon 上的计数器更改为:
平均读取速度为 50MB/秒
平均写入速度为 50MB/秒
这一步需要更多 1 小时 15 分钟..
我认为一切都好,买我不明白发生的事情!
第一步的方式是在非常短的时间内从磁盘读取数据(我认为是 5 秒)
之后,下一步是在很长一段时间内只写入磁盘???
today I do a restore for db of 200G
when the restore start I saw on perfmon that their is only write to the disk
I restore the data files to but no Reading from the source (the same disk).
after 30min of writing in avg of 100MB/sec something to the disk.
The counters on the perfmon change to:
read avg of 50MB/sec
write avg of 50MB/sec
that step take more 1hr, 15min..
I think that everything is OK, buy I don't understand way that happened!
way the first step do a very very short time of reading from the disk (5 sec I think)
and after that the next step was to write only to the disk for a very long time???
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更新
备份步骤 0(可选):根据 BAK 标头描述创建 MDF 和 LDF 文件。可能会导致文件初始化(将新分配的空间中的每个字节清零)。请参阅有关即时文件初始化的误解。
备份步骤1:将备份内容布局到磁盘上。将备份中的位复制到 .MDF 文件中,然后复制到 .LDF 文件中。从.BAK 读取,写入MDF,然后写入LDF。
备份步骤2:对数据库运行恢复。第 1 阶段分析(从 LDF 读取),第 2 阶段是重做(读取 LDF,写入 MDF),第 3 阶段是撤消正在进行的事务(写入 LDF 和 MDF)。
updated
backup step 0 (optional): create the MDF and the LDF files, as per the BAK headers description. May result in file initialization (zero out every byte in the newly allocated space). See Misconceptions about instant file initialization.
backup step 1: layout the content of the backup on disk. copies bits from the backup into the .MDF file, then into the .LDF file. Reads from .BAK, Writes to MDF and then to LDF.
backup step 2: run recovery on the database. phase 1 analysis (reads from LDF), phase 2 is redo (reads LDF, writes to MDF) and phase 3 is undo of in-flight transactions (writes to LDF and MDF).