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Database Protection Turns a Corner

Active-targetという、直接バックアップストレージからデータを読ませられる機能が注目を浴びてきています。

以下、それについてまとめられた記事を簡単に要約して見ます。
http://www.byteandswitch.com/document.asp?doc_id=140753&WT.svl=tease3

通常、DBのリストアは データを戻しがき→トランザクションログをあてる というプロセスで大変時間がかかるが、Active-targetではこのプロセスを省略できる。

Further, once the data is restored, then all the transaction logs since the last backup have to be replayed. With traditional backups, this can be as far back as the previous night, which is again going to slow down the recovery effort.
This is not the case with backup applications that can create an active target. By leveraging disk as more than just “fast tape,” active target-equipped backup apps can create a point-in-time image of the volumes they are backing up.

この機能はCDPの付加機能の一つと思われてきたが、それは間違いであり、CDPとは関係なくバックアップソフトウェアに組み込むことが可能である。

Many people will confuse active targets with continuous data protection (CDP). There is a difference: Active target software is part of the backup application, while most CDP packages are not.

ちなみに、CDPのContinuous Protectionは、DBをBackup Modeで使い続けなくてはいけないため、使われていないことが多いようだ。

Most CDP solutions are capturing changes as they occur, essentially acting as asynchronous mirrors. This typically raises concerns about the quality of the data being sent to the target. Since the servers being protected are often live databases or email servers, you would prefer to put them in a backup mode to insure a clean snapshot of the data.

Unfortunately, this can’t be done every second. There is often an uneasiness about performance impact as well. Because of these concerns, many customers will inactivate (or at least ignore) the constant protection feature, instead choosing specific points at which to perform the protection task. This allows them to snapshot the server to make sure they have an environment that is “in sync” and to determine when the server is not too busy doing other tasks.