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Re: What's the reasonable time to mirror a hard disk?




On Mon, 22 Oct 2001, Yuwen Dai wrote:

> Hi, All
>
> I have two identical hard disk linked with one cable.  The capacity of each
> disk is 40G.  I want to have the second disk be the mirror of the first disk
> by using this command:
>
>   dd if=/dev/hda of=/dev/hdb bs=32k
>
> Nearly 2 hours passed, dd still hadn't finished.  I had to press 'Ctrl-C' to
> stop it.  Is this the right way to mirror a disk?  Or is there some better
> way to do this?  Thanks in advance.

After two hours, the best case is that you were transferring 6MB/sec,
which isn't too bad.  It may have been *just* shy of finishing when you
cancelled it :(

Use hdparm to enable DMA on the disks and see if it speeds up.  If you
don't know how to use hdparm, read its manual page (man hdparm).

-jwb



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