The next question is what the I/O device does with the data. SCSI disks will cache but the scsi layer uses tags and if neccessary turns the cache off on the drive. In other words you should get that behaviour correctly on SCSI media.
The default IDE behaviour doesn't turn write cache off and the IDE device may re-order writes and ack them before they hit storage. IDE lacks tags, and tends to have poor performance on cache flush commands. With the barrier support on the right thing should occur, or with hdparm used to turn the write cache off.
Is this IDE behaviour confined to IDE drives only?
SATA, when using libata, will solemnly be part of the SCSI chain, and hense not subject to your mentioned write cache problem, right?
-- Kind regards, Mogens Valentin
- : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
