Rapid Storage Technology
Intel® RST, RAID
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Write back cache policy data availability

williamfr
Beginner
1,054 Views

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

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David_G_Intel
Moderator
1,016 Views

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 


Regards, 

David G 

Intel Customer Support Technician 


David_G_Intel
Moderator
957 Views

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
Beginner
943 Views

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
Moderator
888 Views

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
Moderator
827 Views

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
Beginner
818 Views
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
Moderator
813 Views

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  


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