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Q: Would you ever want to mix SCSI and IDE drives? What would your Strategy be? How would you do it?

A: Not directly and certainly not within the same system. SCSI hard drives with their super fast data transfer rates are hard to beat for OLTP high performance. The results are mixed for OLAP and OLCP tasks but still clearly superior to IDE drives. A mixture of slower IDE and faster SCSI drives, within the same system, would reduce the overall system to an IDE speed. The speed limit of the system is the speed of the slowest link. As you have all seen, one failing drive in a LUN destroys the effectiveness of that LUN and can reduce overall RAID performance. The slower IDE hard drive system would be good for near-line backup, which is a streaming or bandwidth operation. The advantages of using a SCSI system for the primary and an IDE system for the secondary is very attractive. You get all the benefits of a very fast SCSI system for the primary and a "fast enough", very cost effective IDE hard drive backup system for your data. Disk to disk makes backing up very quick and easy even at IDE speeds. Even though backup is a streaming, or bandwidth intensive, operation the IDE drives with their slower rotational speeds will perform near their rated bandwidth by not having to constantly seek. Unless the disks are very fragmented. For Replication operations, such as miroring or online migrations, and system drives with low frequency access the SATA (Serial ATA) drives are the most cost effective. As prices come down on SATA, and reliability goes up, expect to see Strategy architectures like RAIN (Random Array of Independent Nodes) become popular. RAIN with SCSI was too expensive. RAIN is implemented with RAID systems.

Q: Anybody doing this? Can you mirror SCSI to IDE? Would you want to? How would you do it?