On Tue, Sep 8, 2009 at 05:49, Dwight Schauer<dschauer@xxxxxxxxx> wrote: > Dear fellow Archers, > > I tarred up a couple filesystems and piped the tar stream through ssh > to a remote computer where I dd'ed it to a file. This a common backup > method I've been using for a few years now if I'm going to wipe a > system and start over. > > I'm using JFS on the arch linux system that was being copied to. > > The resulting file ended up being 137G (which is about right based on > the source filesystem usage). > > du --human --total a4b4.tar > 137G a4b4.tar > 137G total > > However, I can only restore from 63G of the tar ball, so I attempted > to see how much could be read. > > dd if=a4b4.tar of=/dev/null > dd: reading `a4b4.tar': Input/output error > 123166576+0 records in > 123166576+0 records out > 63061286912 bytes (63 GB) copied, 1193.69 s, 52.8 MB/s > > There were no critical files in that tar ball that are not kept > elsewhere, that is not the issue. At this point I can consider what is > past the 63G point in the tarball to unrecoverable, which is fine. > > I tried skipping the first 63GB, but that does not work. > > dd if=a4b4.tar skip=123166576 of=/dev/null > dd: reading `a4b4.tar': Input/output error > 0+0 records in > 0+0 records out > 0 bytes (0 B) copied, 27.2438 s, 0.0 kB/s > > It seems like it took a while to figure out that it could not perform > this operation. > > The box in question is running an OpenVZ patched 2.6.27 kernel, but > that might not have anything to do with it. > > Yeah, I know, I could have used bzip and made 2 separate files, I > could have used rsync -av, I could have checked tarball before wiping > the source files systems, etc, that is not the point here. Now that I > know that JFS on my setup has a 63GB file size limit, I know now to > accommodate for that in the future. > > I'm mainly just curious on how the system could write a larger file > than it can read. > > Dwight > I just checked, and the max file size in JFS is 4 petabytes. Seems like you have another problem. -- Anders Bergh
