ただいまAmazon RDSで実運用環境を絶賛構築中！ ドキュメントから運用や構成上で気になるところだけメモしました：
Q: What is a maintenance window? Will my DB Instance be available during software maintenance? Any system changes (such as patching the database software) or modifications you have requested (such as scaling DB Instance class or storage capacity) will be completed within a weekly four hour maintenance window. The only time we will take your DB Instance offline is for backups or software patching; patching should seldom require more than a fraction of your maintenance window, occurs infrequently, and is used only for patches that are security or durability related. If you did not specify a preferred maintenance window when creating your DB Instance, a default value is assigned (such as Sun:05:00-Sun:09:00 UTC for DB Instances in the US-East region). Ideally this window should fall at the time of lowest database usage and thus may need to be modified. If you wish to modify when maintenance is performed on your behalf, you can do so using the ModifyDBInstance API. Each of your DB Instances can have different preferred maintenance windows, if you so choose. For more information on using the APIs or command line interface to specify your maintenance window, please refer to the Amazon RDS Developer Guide.
Q: Does Amazon RDS always update the relational database software with critical patches? Can I opt out of particular patches? Automatically performing critical updates to the MySQL database software powering your DB Instance is a core function of Amazon RDS and cannot be turned off. However, as previously mentioned, you can control the time of the maintenance window when patches are applied to minimize the operational impact of patching. At this point in time, you cannot opt-out of critical patches to the MySQL software. However, you will be informed about upcoming patches via the Amazon RDS forums.
Q: How do I scale the compute resources and/or storage capacity associated with my RDS database instance? You can scale the compute resources and storage capacity allocated to your DB Instance with the ModifyDBInstance API. Memory and CPU resources are modified by changing your DB Instance class, and storage available is changed when you modify your storage allocation. Please note that when you modify your DB Instance class or allocated storage using the ModifyDBInstance API, your requested changes will be applied during your specified maintenance window. Alternately, you can use the “apply-immediately” flag to apply your scaling requests immediately. Bear in mind that any other pending system changes will be applied as well.
Q: Will my DB Instance remain available during scaling? The storage capacity allocated to your DB Instance can be increased while maintaining DB Instance availability. However, when you decide to scale the compute resources available to your DB Instance up or down, your database will be temporarily unavailable while the DB Instance class is modified. This period of unavailability typically lasts only a few minutes, and will occur during the maintenance window for your DB Instance, unless you specify that the modification should be applied immediately.
Q: What is the difference between RDS automated backups and DB Snapshots? Amazon RDS provides two different methods for backing up and restoring your DB Instance(s): automated backups and database snapshots (DB Snapshots). The automated backup feature of Amazon RDS automatically performs a daily backup of your data (during your preferred backup window) and captures transaction logs (constantly). Amazon RDS retains backups of a DB Instance for a limited, user-specified period of time called the retention period, which by default is one day; your database can later be recovered to any point in time within the retention period, up to the last available transaction log. You can use the DescribeDBInstances API to return the latest restorable time for you DB Instance(s).
- DBインスタンスのバックアップ内容は、保持期間（retention period）と呼ばれる指定した期間（デフォルトは1日）だけ保持される
- （RDSのトップページには「up to the last five minutes／最短で5分前まで」と記されている）
DB Snapshots are user-initiated and enable you to back up your DB Instance in a known state as frequently as you wish, and then restore to that specific state at any time. DB Snapshots can be created with the CreateDBSnapshot API and are kept until you explicitly delete them with the DeleteDBSnapshot API. Please note: When you perform a restore operation to a point in time or from a DB Snapshot, a new DB Instance is created with a new endpoint (the old DB Instance can be deleted with the DeleteDBInstance API, if so desired).
NOTE: A brief I/O freeze (typically lasting a few minutes) will occur during both automated and user-initiated backup operations. NOTE: Amazon RDS plans to add a High Availability offering in a future release, which will maintain multiple complete copies of your data in different Availability Zones for greater levels of data durability.
- 異なるAvailability Zoneにデータをレプリケーションする高可用性オプションも将来的に提供予定