Write back cache policy data availability

[williamfr]

Hello!
I have accelerated my RAID 5 with an SSD in write back policy (Maximized performance) with Intel RST. My main doubt is knowing how long will it take for my data written in the cache to get written into the array. I read from the docs that "the data will be written to the array in intervals" but this is a very vague explanation. I have left my computer inactive to see if I hear the data being written to the array (which usually makes some noise) but I hear nothing. I would like to know if I paste a large file into my array, what will be the amount of time where I can assume my data will be safe (aka written into the pool).
Any further information on this topic will be much appreciated.
Thanks

[David_G_Intel]

Hello williamfr

Thank you for posting on the Intel️® communities. Please share with us an RST report and the Intel® System Support Utility (Intel® SSU) results 

• Download the Intel SSU https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility-for-Windows- 
• Open the application and select "Everything" click on "Scan" to see the system and device information. By default, Intel® SSU will take you to the "Summary View".  
• Click on the menu where it says "Summary" to change to "Detailed View".  
• To save your scan, click on "Next", then "Save".  

Regards, 

David G 

Intel Customer Support Technician 

[David_G_Intel]

Were you able to check the previous post?  

Let us know if you still need assistance.    

Best regards,  

David G.  

Intel Customer Support Technician  

[williamfr]

Hello!
Sorry for my late reply. Attached you can find the output of the mentioned program.
I just wanted to say that my question was more theorical as I wanted to know more about when the data is written from the cache to the array.
Thanks!

[David_G_Intel]

Thank you for the information, there is not a specific value that can be provided right now. We are still working on this, the updates will be posted on the thread.

Regards,  

David G.  

Intel Customer Support Technician  

[David_G_Intel]

After further investigation, here is more information; since Maximized performance is the OS file cache as Optane caching is not supported on RAID5. Basically, in this user scenario the OS file cache matters.

The file might be not saved to RAID5 volume because it’s cached by Windows Cache and it’s up to OS to decide when the file will be written to drive and RST has no control. 

For sure it will be saved when shutting down the system and if there is DRAM memory pressure. This can be forced by using the Sync tool from Microsoft, it shall force flushing all data to drive, so you shall “hear” that data is written to HDD after running it:

https://docs.microsoft.com/en-us/sysinternals/downloads/sync

Regards, 

David G 

Intel Customer Support Technician 

[williamfr]

Thank you so much for taking the time to answer my question.
Perfect, that is what I wanted to know.
Best regards

[David_G_Intel]

We're glad to know the information helped. Hopefully, it will help other community members. Since the thread is now solved, we will close it. If you need any additional information, please submit a new question as this thread will no longer be monitored.  

Best regards,  

David G  

Intel Customer Support Technician