On 2013-03-14, at 16:07, Vincent Caron <vcaron@xxxxxxxxxxxxx> wrote: > On 14/03/2013 02:05, Theodore Ts'o wrote: >> Just as a note, e2fsck -v can sometimes get this information much more >> quickly than other alternatives, since it can scan the file system in >> inode order, instead of the essentially random order. >> >> Just as a side, if you just want to get a rough count of the number of >> directories, you can get that by grabbing the information out of >> dumpe2fs. > > Very useful. Global stats without having to scan the whole filesystems > are very precious... > > I was wondering : couldn't we use dumpe2fs or something based on > libext2fs to quickly extract a snapshot of all inodes from a given > filesystem ? For incremental backups, simply checking the mtime on > millions of inodes and discovering that only a handful of them were > updated since the previous pass looks very inefficient with > readdir()+lstat(). That's exactly what e2scan does. I'm pretty sure that is in upstream e2fsprogs now (not just our Lustre version), but I'm on a plane and cannot check. It will scan the inode table directly and can generate the pathnames of files efficiently. It can filter on timestamps. Cheers, Andreas > So mnay syscalls, so man spoonfed bits of > information. When I had a peek, I tought I'd got a list of inodes but > would not be able to link them back to their name(s) without inducing > the same cost as a regular find-like filesystem traversal. Does it make > sense ? > > AFAIK I would be better served with block-level snapshot solutions, > but LVM snapshots are supposed to double your writes if I got it right, > and I'm not sure there's something else in the Linux and free software > world. Plus I'd love to not migrate away from my ext3/4's without a > compelling reason. Btrfs is not (yet) and option and ZFS doesn't fit > legally with Linux. > > _______________________________________________ > Ext3-users mailing list > Ext3-users@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/ext3-users _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
