Date: Wed, 15 Mar 2006 14:28:00 +0000 From: Alex Zbyslaw <xfb52@dial.pipex.com> To: Jerry McAllister <jerrymc@clunix.cl.msu.edu> Cc: freebsd-questions@freebsd.org Subject: Re: dump level 9 Message-ID: <44182470.5060902@dial.pipex.com> In-Reply-To: <200603151345.k2FDjY88027421@clunix.cl.msu.edu> References: <200603151345.k2FDjY88027421@clunix.cl.msu.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
Jerry McAllister wrote: >But, I wonder why you chose level 9 for your change dumps. It sort >of defeats the system. It would be more normal to use level 1. >I know that [some much] earlier versions of BSD dump only took levels >up to 5, but I presume that since they include up to 9 in the documentation >it should work. > > If you only use one level other than 0, then it makes no difference what that level is: 1, 9, 5 anything but 0. A level N dumps everything since the last dump < N, which in this case is always the last level 0. Using "modified tower of hanoi" (so the man page says :-)) can decrease the amount of data per dump at the cost of having to do more dumps: e.g. I do 0: 1 3 2 1 3 2 ... 0 ... But if I have to restore everything and the last dump was a 2, I have to restore the 0 1 and 2. Similarly if it crashed after 3, I would do 0 1 3. That cuts down the amount of data dumped, but is slightly more complex than just having to restore the 0 and last 9 (in the OPs case). I could use 1 7 9, or 4 6 8 instead of 1 2 3 and the data dumped would be the same in each case. I was pretty sure that BSD 4.2 had 9 incremental dump levels, but that was long, long ago in a universe of 1600bi tapes far, far away :-) --Alex
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?44182470.5060902>