|New Instance Type||Amazon EC2 now supports a new instance type: micro (t1.micro). Micro instances provide a small amount of consistent CPU resources and allow you to burst CPU capacity when additional cycles are available. They are well suited for lower throughput applications and web sites that consume significant compute cycles periodically.
Micro instances are available on both 32-bit and 64-bit platforms, but only as Amazon EBS-backed instances.
For more information about the new instance type, including appropriate applications for it, go to:
|Current Limitations for Micro Instances||Following are current limitations of micro instances:
|Current Limitations for Cluster Compute Instances||Following are current limitations of cluster compute instances:
|Current Limitations for Cluster Placement Groups||Following are current limitations of cluster placement groups:
|Setting the TCP_MAXSEG Socket Option||The 2.6.18-164.15.1 kernel used in the CentOS 5.4 reference AMI (ami-7ea24a17) contains a known issue where setting the TCP_MAXSEG socket option on TCP sockets to certain values (known values include 1500) causes the kernel to generate TCP Segmentation Offload (TSO) packets of invalid size that are then dropped by the NIC driver, resulting in very low network throughput. Don't set this socket option and let the kernel handle segmentation and Path Maximum Transmission Unit (PMTU) discovery using the default settings.|
|Query Version of ModifyInstanceAttribute||The Query API ModifyInstanceAttribute request does not allow you to modify the block-device-mappings, and you can't modify the user-data attribute if it already contains data.|
|Paid AMIs Backed by Amazon EBS||Amazon EBS-backed AMIs are not currently supported by Amazon DevPay.|
|Windows AMI launch times||Windows AMIs take longer to launch than Linux/UNIX instances due to larger AMI sizes and multiple reboots.|
|Windows AMI sizes||Installing software on Amazon S3-backed Windows AMIs can cause them to become large and easily reach the 10 GB limit. Before bundling, check the size of the C:\ volume.|
|Limitation on drive mapping||There are limitations on devices available for storage attachment. For more information, go to How to Attach the Volume to an Instance in the Amazon Elastic Compute Cloud User Guide.|
|Instance limit||New users are limited to a maximum of 20 concurrent instances, but many of our customers use hundreds or thousands of instances. If you need a higher limit, go to http://aws.amazon.com/contact-us/ec2-request.|