Andre Majorel wrote: > > On 2007-08-21 05:55 -0400, Matt McCutchen wrote: > > On 8/20/07, Andre Majorel <[EMAIL PROTECTED]> wrote: > > > Is there a way to make rsync look inside device files ? > The goal is > > > to copy the contents of a block device to a regular file > > > incrementally. > > > > > > Short of that, even just getting it to dump the block > checksums of > > > the content a block device would help (if I know which blocks are > > > out of sync, I can fix them with dd). > > > > Are the block device and the target regular file on the > same machine? > > They could be. Or not. Doesn't matter. > > > Your remark about dd suggests that they are. > > Not necessarily. > > dd if=myfile skip=100 | ssh [EMAIL PROTECTED] "dd of=myfile > seek=100 conv=notrunc" > > > If so, why do you want an incremental copy? It does at > least as much > > disk I/O as an ordinary copy (since it reads the entire > basis file), > > and the reduction in data passed from the sender process to the > > receiver process is irrelevant. > > Sometimes, you need to copy a whole block device and you > can't just cat it to wherever you want, go out to lunch and > expect it to work. > > The destination could be unreliable. The network could be > unreliable. The source could trigger DMA timeouts and lock up > the bus, forcing you to reboot. Many things can and do go wrong. > > In those situations, you need to be able to verify that the > copy is identical to the original and where's it's not, fix > it (NOT start over, because if it failed the first time, it > may fail the second time). > > rsync already has most of the mechanisms to do that easily > and efficiently. It would be even better if it could complete the copy > *first* and check the beginning *second* but that's probably > more involved. > > > Anyway, the attached patch for the current CVS rsync adds an option > > --copy-devices that makes rsync copy the contents of source device > > files as if they were regular files. I tested the option on my > > computer to copy a block device to a regular file locally, and it > > seemed to work. Wayne, you might like to include this patch in the > > patches/ dir of the source distribution. > > Thanks for the patch. I hope something like that goes in. I > understand rsync was not meant as a block-device-level copy > tool, but since it already has most of what it takes, it's tempting. >
Could be extremely useful (in some cases) but beware of rsync of /dev/zero and friends One very useful stunt is an rsync that takes a reasonable amount of time followed immediately by an rsync that takes a very short amount of time ??an offsite full-disk-backup of a moving target almost feasible?? -- To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
