On Fri, 11 Oct 2002 07:26:32 +0800, Ieong Sze Chung Ricci <ricciat_private> said: > However, I could not find any information about the time required > for dd to clone a hard disk of 20G, 30G. This is because there's *so* many variables involved: How fast the source and target disks are (both RPM wise and data transfer rate). How fast/capable your disk controller is. Whether both disks are on one controller or on separate controllers. What parameters 'dd' is invoked with, and how they interact with the I/O subsystem of your kernel. Whether your kernel supports DMA/etc for that hardware config. What speed your system is. 'hdparm -T -t /dev/hda' (change 'hda' as needed to match your drive) will give you a quick test of raw disk speed. As a rough guideline, several systems I tested here report between 21 and 35 mbytes/second - so you're looking at roughly 5 to 10 minutes per 10G of disk. So figure "under an hour" for everything, including plugging in cables/etc. If you're trying to do a 'dd | netcat', then network bandwidth enters into it as well, etc etc etc. Don't try it on a 10mbit line unless you have all night.. ;) -- Valdis Kletnieks Computer Systems Senior Engineer Virginia Tech
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