#acl merlyn:read,write All:read

= ISM Day 4 =
== Backup & Recovery ==
  * 单纯以恢复已丢失或损坏的数据为目的而另外创建并保留的生产数据的拷贝。

== NDMP ==
  * 备份数据直接从NAS发送到备份设备（不再需要通过应用程序程序服务器来传输数据）。
  * 在NAS客户端不需要安装NDMP客户端。
=== NDMP Client ===
  * installed as add-on software on backup server.

=== NDMP Server ===
  * NAS 机头用作执行备份并将数据发送到备份设备的NDMP服务器(NAS机头使用其数据服务器从存储中读取数据，然后直接发送到备份设备）
  * Only backup metadata is transferred over production LAN
== VMAX 直接主存储备份方法 ==
  * 无需额外的备份软件，将数据直接从主存储系统备份至备份存储。

== deduplicate ==
=== File based ===
=== Segment Fixed ===
  i. VNX 8K
  i. ABC|EFG|HIG
  i. aAB|CEF|GHI|G
=== Variable Fixed ===
  i. Data Domain 4k-12K
  i. Avarma 1k-64K
  i. ABC|EFG|HIG
  i. aABC|EFG|HIG

== Content Addressed Storage(CAS) - An Archival Solution ==
  * CAS的主要特性
  i. 数据完整性
  i. 内容真实性
  i. 单实例存储
  i. 强制执行保留
  i. 可扩展性

== Snapshot ==
  i. 当后面B快照包含了前面A快照的共享数据时，此时快照需要整合。
  i. 删除快照应该从最旧的快照开始。

=== CoFW: Copy on First write ===
  i. 先苦后甜
=== RoW: Redirect on Write ===
  i. 先甜后苦

== Remote Replication ==
=== 同步(Synchronous) ===
  * Write is committed to both the source and the remote replica before it is acknowledged to the compute system.
  * Allows to restart business operations at a remote site with zero data loss ( Provides near zero RPO!)
=== 异步(Asynchronous) ===
  * Write is committed to the source and immediately acknowledged to the compute system.