Instance status checks failures

[ljp0101]

I've observed several instance failures in our production environments during the last month. Curious what's happening as this is something new and highly disruptive.

From today:

Terminating EC2 instance: i-060975c314a198677 At 2024-05-07T16:11:59Z an instance was taken out of service in response to an EC2 instance status checks failure.

[ljp0101]

Happened to us again today:

Terminating EC2 instance: i-0c4267833705d8d9c At 2024-05-22T13:59:51Z an instance was taken out of service in response to an EC2 instance status checks failure. 2024 May 22, 05:59:51 PM +04:00

[ljp0101]

Again:

Terminating EC2 instance: i-0a74638e8ea8a0844 At 2024-05-23T12:09:03Z an instance was taken out of service in response to an EC2 instance status checks failure. 2024 May 23, 04:09:03 PM +04:00

[ljp0101]

Again:

Terminating EC2 instance: i-05023a2fab96c88f9 At 2024-05-25T16:10:40Z an instance was taken out of service in response to an EC2 instance status checks failure.

[ljp0101]

Again:

Terminating EC2 instance: i-0dbc92d566e694e79 At 2024-05-27T04:21:18Z an instance was taken out of service in response to an EC2 instance status checks failure.

[ljp0101]

Terminating EC2 instance: i-00f1d4ba1fa292dbd At 2024-05-31T22:30:42Z an instance was taken out of service in response to an EC2 instance status checks failure.

It seems like there's a 1-2% chance of failure per 24 hours of uptime recently. I can't imagine this level of unreliability would be tolerated with any other instance type.

This is happening across multiple accounts, multiple zones in us-east-1, two different bitfiles, single software architecture / fpga drivers.

The error message suggests a pure AWS issue. It wouldn't surprise me if we're contributing to the failures somehow but nothing to go on based on the error message.

[AWSjoeluc]

Hello,

Thanks for reaching out with this issue. We've been internally monitoring the issue and will report back soon. In the mean time, have you been able to follow some of the AWS EC2 troubleshoot steps?

• https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstances.html

[ljp0101]

Looked over the link with devops and most of it doesn't make sense in our context because it's primarily about configuration problems and this happens after instances run for extended periods. It look like there may be a more specific cause available if we can check the EC2 console and see the instance's details but they're in an autoscaling group so get automatically terminated and details become inaccessible on the console quickly.

Questions I have are:

1) Are the status checks failures unique to my accounts?

2) Do you know the specific reason for the status checks failure (e.g., a networking problem)?

3) Is there anything we could be doing with the FPGA that can cause a status checks failure (e.g., hanging the PCI bus)?

Happy for you to close the support ticket if it helps your KPIs. I don't need this solved urgently but it is problematic from the perspective of our customers so I don't want it ignored either.

[AWSjoeluc]

One thing that may be contributing to the instance instability are PCIe/AXI errors on the bus. Can you provide the shell timeout data immediately prior to the instance failures? You can find more information on collecting this data with the SDK here: https://github.com/aws/aws-fpga/blob/863d963308231d0789a48f8840ceb1141368b34a/hdk/docs/HOWTO_detect_shell_timeout.md

Gathering the data above will help us narrow down the issue as "hanging the PCI bus" is the most likely root cause of the issue. Don't worry about closing the support tickets, it helps us collect data and gain visibility on the issues!

[ljp0101]

Added below to the cleanup hook, which might provide some insight. I know OCL reads are working fine immediately prior to the status checks failure.

// print fpga metrics from aws-fpga cli tool, checks for shell timeouts
std::system("sudo fpga-describe-local-image --headers --metrics --fpga-image-slot 0 &> fpga-metrics.log");
std::cout << std::ifstream("fpga-metrics.log").rdbuf();

[AWSjoeluc]

Could you share what shell interfaces your workload is exercising at the time of failures?

[ljp0101]

We didn't change anything except for rebuilding the image to add above code and haven't experienced the problem in the last two weeks so might be gone.

OCL and DMA_PCIS. We do DMA writes to two DDRs from the processor, read from two DDRs to the FPGA, and reads & writes between the processor and FPGA with OCL registers.

[AWSjoeluc]

We're glad to hear you're no longer experiencing the issue. If you ever do experience the failure again, please reach out with any information you have!

[ljp0101]

Autoscaling group:

Terminating EC2 instance: i-09fcd9b811c50579c At 2024-07-21T18:55:33Z an instance was taken out of service in response to an EC2 instance status checks failure.

EC2 console:

Instance reachability check failed

fpga-describe-local-image:

Error: (21) afi-command-malformed A malformed response from the FPGA API can indicate that the FPGA has stopped behaving correctly and the instance will need to be stopped and and restarted. If this continues to happen (after an instance restart), this may be an indication that your AFI is exceeding allowed power consumption limits.

I find the generic reasons for a reachability check failure implausible given OCL reads and DMA writes aren't erroring immediately prior to the fpga-describe-local-image call.

There's usually an associated issue that comes from within our logic where we have a processing operation timeout when there's a status checks failure. I am aware of the timeout from successful OCL reads. We've had these timeouts happen before with functional problems in our design but I struggle to see how anything we do in the CL or with DDR could cause a reachability failure.

Representative power consumption from a working instance:

Power consumption (Vccint): Last measured: 9 watts Average: 36 watts Max measured: 54 watts

Any further thoughts?

[ljp0101]

Autoscaling group:

Terminating EC2 instance: i-067ca8584abf6b911 At 2024-07-29T17:20:00Z an instance was taken out of service in response to an EC2 instance status checks failure.

EC2 console:

Instance reachability check failed

fpga-describe-local-image:

Error: (21) afi-command-malformed A malformed response from the FPGA API can indicate that the FPGA has stopped behaving correctly and the instance will need to be stopped and and restarted. If this continues to happen (after an instance restart), this may be an indication that your AFI is exceeding allowed power consumption limits.

Same deal.