For the second part of your question, the answer is "yes". All RAID functions specify using identical drives. Striping...
different size drives lowers the performance to the lowest common denominator. Larger drives will have a higher average seek time (assuming same rotational speed.) Although what you suggest is doable, most will not recommend it or support it.
And, for the final part of your question, response performance of the first drive will be negatively affected by the lower speed second drive. Again it's doable, but most will not recommend or support this. You are opening yourself up to errors as well. You are better off using asynchronous mirroring between arrays where the second array has lower cost and speed drives.
Dig Deeper on RAID
Related Q&A from Marc Staimer
When compared with earlier Serial ATA standards, SATAe is more advanced, reduces latency, has a higher performance level and offers backwards ...continue reading
Latency in object stores that stems from a large amount of metadata means the technology is better suited to non-transactional data.continue reading
Eventual consistency in object stores can be an issue because object storage is spread over many nodes and up-to-date data may not always be ...continue reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.