Messages in this thread |  | | From | "H. Peter Anvin" <> | Subject | Re: Dump corrupts ext2? | Date | 10 Oct 2001 19:57:50 -0700 |
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Followup to: <20011010173449.Q10443@turbolinux.com> By author: Andreas Dilger <adilger@turbolabs.com> In newsgroup: linux.dev.kernel > > > > I'm pretty sure this is because dump reads the block device directly > > (which is cached in the buffer cache), while the file data for cached > > files lives in the page cache, and the two caches are no longer > > coherent (as of 2.4). > > In Linus kernels 2.4.11+ the block devices and filesystems all use the > page cache, so no more coherency issues. >
How do you find a random block in the page cache? Last my understanding was that the page cache is organized by inode/offset, which wouldn't lend itself to looking up a random hardware block.
(Not to mention the fact that the filesystem is perfectly allowed not to present anything like a coherent state to the disk while mounted, which means that even if you did a snapshot in time you're not guaranteed to have anything functional. I understand this can be done by sending a "quiet point" command to the filesystems, followed by an LVM snapshot, but I doubt may people do that!
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