Intel CAS bug

[Emjayen]

I'm observing some unusual behavior with Intel's Cache Acceleration (CAS) software where-in a system worker thread will enter what appears to be an infinite loop, pinning a single core inside its KM driver (IntelCAS.sys). During this state, I/O irrespective of cached-state (hit/miss), continues to succeed.

This issue occurs anywhere from half an hour to several from starting the cache while configured in write-through mode. This behavior can also be reliably reproduced by setting CAS to write-back and generating substantial I/O. Note that during this mode, flushing the cache to disk (by stopping the cache, or shutting down) will frequently stall; all time is in KM during an IOCTL (NtDeviceIoctl) -- I've given it hours to complete without avail.

Profiling with VTune doesn't reveal much; it appears to be spending all its time memcpy'ing.

Note that, originally I was interested in leveraging Intel's "Smart Response Technology", however this both appears to be deprecated for non-Optane SSDs in the latest RST software -- I assume this is correct?

I've attached system information.

Thanks,

Matt.

[JosafathB_Intel]

Hello Emjayen,

Thank you for contacting Intel® Memory & Storage Support.

As we understand, you need assistance regarding Intel® Cache Acceleration Software / Open CAS Linux, to further assist you, please provide us with the following information:

• We will like to know the version/release of CAS you are using.
• Are you using Open CAS, or are you using the licensed version of our software?
• Do you have an Intel® SSD in your current configuration? If you do, would you mind providing us the model and capacity of the drives?

We will be looking forward to your reply.

Best regards,

Josh B.

Intel® Customer Support Technician

A Contingent Worker at Intel®

[Emjayen]

Hi Josh,

I'm using "Intel Cache Acceleration Software for Windows OS" version 3.2.2.64 with a trial license.

I am not using an Intel SSD, rather: "NVMe Samsung SSD 970, 1TB"

-Matt

[JosafathB_Intel · Accepted solution]

Hello Emjayen,

Thank you for your reply.

Seems to be that you are using hardware that is not supported by the Intel® Cache Acceleration Software, and based on the information you provided and your current configuration, our recommendation is to move to the Open CAS project (https://open-cas.github.io/) which is an Open Source project.

The Open CAS project is “community supported” if you are using any SSD different than Intel® Optane™ SSDs this project is the best option for you.

This open community is currently hosted here: https://github.com/Open-CAS

We have support licenses available in case you are interested please, let us know if you do, to engage communication with the team in charge.

If you need further information, please visit:

https://www.intel.com/content/www/us/en/support/articles/000006420/memory-and-storage/ssd-software.html

We hope you find this information helpful.

Have a nice day.

Best regards,

Josh B.

Intel® Customer Support Technician

A Contingent Worker at Intel®

[JosafathB_Intel]

Hello Emjayen,

We were reviewing your community thread, and we would like to know if you were able to review our previous post and if you needed further assistance.

Have a nice day.

Best regards.

Josh B.

Intel® Customer Support Technician

A Contingent Worker at Intel®

[JosafathB_Intel]

Hello Emjayen,

We were reviewing your community thread, which is related to the Intel® Cache Acceleration Software, and we have not heard back from you in a while, so we will proceed to close this inquiry now.

If you need further assistance, please post a new question.

Best regards,

Josh B.

Intel® Customer Support Technician

A Contingent Worker at Intel®