SAS/SATA Mixed Pool and Initial Data Placement

Question

Assuming I have a mixed pool of SAS and SATA, where do new writes land?  My concern is that writes happen on both SAS and SATA equally and then over time the the data on the SATA would be moved to SAS if it needs the high performance and if data on SAS is cold it moves to SATA. I'm leaning toward a configuration that initially writes everything to SAS assuming it should be high performance and then over time, move it down to SATA.  It seems that this should be possible. I'm looking for clarification and maybe a document that could help me understand how to configure my array to land everythying on fast and move down to slow over time.

DamonH · Answer

Thank you for the information.  For performance sensitive volumes (database) my impression is that I will be binding the volume to the high performance SAS RAID 10 member and not risk the write penalty and performance penalty of initially writing directly to the RAID 50 SATA member.  Is my opinion on par with other admins?

FluidFS

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