While testing out a new sg driver, I have stumbled across an impressive speed-up in disk to disk copy times. This may only be on my hardware but I hope others can get similar results on their equipment. The timed test involves copying one disk to another. Both disks are IBM model DCHS04U which hold 4.4 GB each and have average continuous streaming rates of about 9 MB/sec (on both reads and writes). The test is the elapsed time that a copy takes: # dd if=/dev/sda of=/dev/sdb bs=512 This took about 30 minutes. Bypassing buffering and using the sg interface with "sg_dd" brought this time down to 24 minutes. Using another variant called sgq_dd that queues both reads and writes asynchronously brought this time down to 9 minutes 20 seconds. Just reading a disk and throwing away the result takes about 8 minutes 50 seconds (i.e. "dd if=/dev/sda of=/dev/null"). Paying an extra 30 seconds to write that 4.4 GBytes to another disk seems like a pretty good deal. There is more information at: http://www.torque.net/sg [follow fast copy link] Are there other Linux/Unix utilities that give this type of performance? Doug Gilbert - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED]
