Comments on: Tagged Command Queuing http://www.santrainingblog.com/2010/06/tagged-command-queuing/ Storage Area Networking Wed, 26 Oct 2011 02:06:29 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: ocozette http://www.santrainingblog.com/2010/06/tagged-command-queuing/comment-page-1/#comment-30 ocozette Mon, 21 Jun 2010 16:41:38 +0000 http://www.santrainingblog.com/?p=288#comment-30 There are also another tiny benefit, queuing! We have the time to transfer data over the SATA bus, and the time consumed by disk controller to read/write to the disk. So, with NCQ (and SCSI with TCQ) the total time is the maximum of these two times, with the old ATA/IDE drive it was the sum of these two times. However, the SATA bandwidth is higher than disk speed, so it's only 10 to 15% of improvement. There are also another tiny benefit, queuing!

We have the time to transfer data over the SATA bus, and the time consumed by disk controller to read/write to the disk.

So, with NCQ (and SCSI with TCQ) the total time is the maximum of these two times, with the old ATA/IDE drive it was the sum of these two times.

However, the SATA bandwidth is higher than disk speed, so it’s only 10 to 15% of improvement.

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