How to: EBS Gotchas and Limitations
-	❗EBS durability is reasonably good for a regular hardware drive (annual failure rate of [between 0.1% - 0.2%](http://aws.amazon.com/ebs/details/#availabilityanddurability)). On the other hand, that is very poor if you don’t have backups! By contrast, S3 durability is extremely high. *If you care about your data, back it up to S3 with snapshots.*
-	🔸EBS has an [**SLA**](http://aws.amazon.com/ec2/sla/) with **99.99%** uptime. See notes on high availability below.
-	❗EBS volumes have a [**volume type**](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html) indicating the physical storage type. The types called “standard” (**st1** or **sc1**) are actually old spinning-platter disks, which deliver only hundreds of IOPS — not what you want unless you’re really trying to cut costs. Modern SSD-based **gp2** or **io1** are typically the options you want.
-	❗When restoring a snapshot to create an EBS volume, blocks are lazily read from S3 the first time they're referenced. To avoid an initial period of high latency, you may wish to use `dd` or `fio` as per the [official documentation](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-restoring-volume.html).

EFS
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