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Write Verify was removed mostly because no OS used it. And it was a PIO Data Out command and no one wanted to define a DMA version of the command (because no OS was using the existing command). Plus there was the nasty problem of just what does "verify" mean. Verify on an ATA drive traditionally did not require the device to read data from the media. If the data to be "verified" was in the drive's cache (because it was recently read into that cache) then it was assumed there was no need to read the media again. This is different from SCSI where there is a traditon that says "verify" means read the media (and that may require a cache flush first?). And here then we have a new issue... Is Write Verify really also a Flush Cache command??? *** Hale Landis *** www.ata-atapi.com ***
