On Fri, Jan 11, 2008 at 09:51:31AM -0700, Alberto Treviño wrote: > > In the Linux kernel, SATA was built upon the SCSI framework because of > its many similarities. Hence, any SATA drives that used the correct > SATA driver (rather than IDE) would show up as /dev/sd*.
My understanding corresponds with everything Alberto just said. Let me add a bit more (and possibly expose my ignorance). Traditionally, SCSI was always the expensive industry-grade hardware, and cheaper stuff like IDE (a.k.a. Parallel ATA or PATA) was used in home systems. SCSI hardware was almost always faster and more reliable. If I remember correctly, ATAPI (like what CD drives use) is basically a limited SCSI command set over an IDE interface. That was basically the first time we started seeing SCSI stuff in commodity PCs. Then they decided to do come up with the successors to SCSI and PATA and decided that serial would be better than parallel. SAS would be the successor to SCSI in terms of being the expensive, fast, and reliable hardware, and SATA would be the successor to PATA in terms of being cheap. If I understand correctly, SAS is just SCSI over a low-level serial connection. SATA is basically a dumbed-down SAS. SATA uses a restricted SCSI command-set, which means that SATA electronics are cheaper to make than SAS hardware. As Alberto said, sometimes a machine will make a SATA drive appear to be an IDE drive to the OS. But normally, a SATA drive looks like a SCSI drive because it basically is a SCSI drive. And as Alberto said, now even IDE drives are called sda, sdb, etc., since the new libata in the kernel has ties to SCSI. Is that all correct? -- Andrew McNabb http://www.mcnabbs.org/andrew/ PGP Fingerprint: 8A17 B57C 6879 1863 DE55 8012 AB4D 6098 8826 6868
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