On Thu, 11 Dec 2003, Dan Nelson wrote:
> In the last episode (Dec 11), Matthew Seaman said: > > On Thu, Dec 11, 2003 at 02:54:12PM -0500, Dru wrote: > > > Can anyone describe or point me to resources explaining why it is > > > dangerous to dd a filesystem while it is mounted? Is it still > > > considered to be dangerous if the system is first dropped down to > > > single-user mode? > > > > Remember that dd(1) traverses the block device sequentially, but that > > most FS accesses are random, so any particular change can span either > > side of dd(1)'s offset. Also that dd'ing from the block device > > bypasses the usual machinery for doing file IO -- machinery that is > > designed under the premise that it will have sole control over what > > gets read or written where and when. > > On current you can get around the consistency problem by dd'ing a > snapshot of the filesystem, just like dump's -L flag does. You mean, run "makesnap_ffs" first? I've been meaning to play with that one, I'll have to try it out. Dru _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
