I have a question about DCS3700's Enhanced Power-Loss Data Protection:
according to Intel DCS3700 spec: Enhanced Power-Loss Data Protection will save all cached data in the process of being written before shutting down.
So here is the question:
Imagine this case , if host send several write cmd to ssd and ssd compelete some cmd with returning fis ok. In the process of one write cmd, the ssd shuts down without returning fis ok to the host.
Note that all data of the acknowleged cmd and part of data of un-acknowleged cmd are in the ssd's cache.
The question is : according to Enhanced Power-Loss Data Protection, if all cached data will be written to flash, will s3700 make sure the un-acknowleged cmd data still valid?
You're correct. As long as it was captured in the temporary buffers, it should be saved to the NAND, regardless of the status of the command.
During an unexpected power loss or "unsafe shutdown" this feature allows the firmware routines in the SSD to respond and make sure both user and system data in the temporary buffers are transferred to the NAND media.
Additionally, given the energy provided by the capacitor elements and urgency to recover data, firmware de-prioritizes non-essential controller activities to quickly get into data saving mode, with no impact to overall system performance.
"How Power-Loss Data Protection is Implemented The Intel SSD DC 3700 Series contains hardware- and firmware-based power-loss data protection features. The SSD includes a power-fail detection circuit, which sends a signal to the ASIC controller in the SSD indicating there is an imminent drop in power level. Triggered by this, SSD firmware disconnects the input power from the SSD. The SSD then relies on its on-board power-loss protection capacitance to provide enough energy for the SSD firmware to move data from the transfer buffer and other temporary buffers to the NAND."
- http://download.intel.com/newsroom/kits/ssd/pdfs/Intel_SSD_DC_S3700_Product_Brief.pdf Intel® Solid-State Drive DC S3700 Series - Product Brief
Please let us know if this answers your question.
But I still want to know that, how do you test this pattern?
Because our team is going to make a product with intel DC series, but we do not have test method to check if it behave as you said.It will be more helpful if you can provide us some test method.
As you know, if we need to check wether all cached data is written to nand, we need a method to cut ssd power in the process of a SATA write cmd.
I wonder if we need to write sata driver by ourself in Linux, or is there any ready-made application or software can help ?
We're not currently aware of any publicly available tool or method to test this feature.
I will research this further and let you know what we find.
After some research, I was unable to find a tool aimed directly at testing this feature. We were able to find some examples of third parties who tested our drives similarly, perhaps their tests may be a good starting point for your purposes.
- https://hardware.slashdot.org/story/13/12/27/208249/power-loss-protected-ssds-tested-only-intel-s350... Power-Loss-Protected SSDs Tested: Only Intel® S3500 Passes.
- Report: http://lkcl.net/reports/ssd_analysis.html http://lkcl.net/reports/ssd_analysis.html.
According to the product specification document for the DC S3700 Series, the drive "supports testing of the power loss capacitor, which can be
monitored using the following SMART attribute: (175, AFh)."
- http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/ssd-dc-s3700-spec... Product Specification Document, Page 13, Sec 2.8.
You may also find the following document helpful, as it goes into detail explaining how the technology behind the Enhanced Power-Loss Data Protection feature works.
- http://www.intel.com/content/dam/www/public/us/en/documents/technology-briefs/ssd-power-loss-imminen... Intel® Power Loss Imminent (PLI) Techonogy.
Note: Any links provided for third party tools or sites are offered for your convenience and should not be viewed as an endorsement by Intel® of the content, products, or services offered there. We do not offer support for any third party tool mentioned here.
We hope this information helps.
It seems that they only provide their test result, but what we need is a method to test,we can not judge practicability in theory.
It is not that we don't trust Intel,we know that Intel is trust-worthy, but we need to make a report of power-loss-protection feature of SSDs, therefore we can only test it by ourself.
I heard that a software call DriveMaster from ULink Technology Coperation can exclude MotherBoard's SATA controller, so that the software can control SSD directly under the user script.
I wonder if you ever heard of this software and is this software helpful if we write script by ourself.
More over I also wonder how did Intel test S3700 SSD's Power loss protection feature? Do you wrote Window driver or Linux driver by yourself?
If it is very difficult or complex to test this pattern, we have to delay our project.
Unfortunately we do not have any public methods that we can release for you to perform these tests.
You may need to create an account and contact our Resource & Design Center. They may be able to provide you with the tools or documentation you need.
- http://www.intel.com/content/www/us/en/design/resource-design-center.html Resource & Design Center for Development with Intel®.
- http://www.intel.com/content/www/us/en/design/account-support.html Intel Account Support.
We hope this helps.