Date: Fri, 13 Jan 2006 09:14:38 +0100 From: "Christoph P. Kukulies" <kuku@kukulies.org> To: Peter Jeremy <PeterJeremy@optushome.com.au> Cc: Christoph Kukulies <kuku@www.kukulies.org>, freebsd-hackers@freebsd.org Subject: Re: increasing dd disk to disk transfer rate Message-ID: <20060113081438.GA4401@kukulies.org> In-Reply-To: <20060112211300.GB13244@cirb503493.alcatel.com.au> References: <200601120948.k0C9mcqR092895@www.kukulies.org> <20060112211300.GB13244@cirb503493.alcatel.com.au>
next in thread | previous in thread | raw e-mail | index | archive | help
Thanks, folks, for the interesting contributions. I really should have marked the subject "OT" but there spring up a lot of interesting ideas. On Fri, Jan 13, 2006 at 08:13:00AM +1100, Peter Jeremy wrote: > On Thu, 2006-Jan-12 10:48:38 +0100, Christoph Kukulies wrote: > >dd if=/dev/ad2 of=/dev/ad3 conv=noerror > > > >The process is running now since yesterday evening and it is at 53 MB > >at a transfer rate of about 1.1 MB/s. > > > >In case the the result being unusable I would like to find a way to make this > >copying faster. > > Note that whilst increasing the DD blocksize will speed up the > transfer, it will also increase the amount of collateral damage when a > hard error occurs. If you rummage around the ports or tools tree, > you'll find a utility (its name escapes me but I believe it was > written by phk) that is designed to do disk-to-disk recovery - it /usr/src/tools/tools/recoverdisk I fired up this tool yesterday night and it is still running. Ah yes, it runs forever unless it empties the queued failed block reads. It writes out a line of numbers (which are a bit difficult to understand). I think the suggestion to do a filewise recovery would be the best since it will be very unlikely > copys data in big slabs until it gets an error and then works around > the faulty area block by block. > > You should also install /usr/ports/sysutils/smartmontools - this > handles S.M.A.R.T. Yes, but what would smart help me further with recovery? > > >Is there a way to tweak the driver (be it the FreeBSD promise driver > >or the normal ata driver) to use more retries on errors so that I > >have the chance to copy everything or nearly everything of the already > >degrading hard disk? > > A quick look at the ata driver suggests that there are a number of > 'retry' and 'retries' variables/fields. I suspect you could increase > the number of retries if you wanted to patch the driver. Thanks for the help. -- Chris Christoph P. U. Kukulies kuku_at_kukulies.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20060113081438.GA4401>