e2compr: Software

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There is a file format difference between e2compr-0.3.x and e2compr-0.4.x.

If you are using kernel 2.0, then you are stuck with e2compr-0.3.x (unless you move to kernel 2.2).

If you are an existing e2compr user, you might as well wait a bit before switching to 0.4. In the meantime, I have more chance to smoothen the transition for you (see next section).

0.3.x Software

0.4.x Software

Moving from e2compr-0.3 to e2compr-0.4 involves decompressing and/orremoving everything under 0.3, and restoring/recompressing it under0.4. You must do `chattr -c’ to everything before movingto 0.4 — even to directories.

I’m preparing some programs to help people do this. The main thing left to do is to modify e2compress to have a mode where it just looks for problems in files rather than compressing or decompressing. It is important to find any problems before archiving and restoring everything, because otherwise the problems could just get hidden, in which case you’d have corrupted files without even knowing about it.

For those that wish to perform the transition without waiting, some broad instructions follow. You might like to print off a copy.

  1. Look for attribute problems among your existing files. find mountpoints -xdev -attr +XED -print0 |xargs -0 lsattr -dFiles with the `X’ attribute (shown in earlierversions of lsattr as `*’) are beingaccessed in raw form. This means that de/compression isn’t being done for them. Run e2decompress on the file, just in case someone accidentally wrote to the file in this raw mode. (The `chattr +X’ means of accessing raw data will be removed from a later version of e2compr. It really is a broken interface.)Files with the `E’ attribute may have a compression error. Try running e2decompress on these files, take note of any warning message you see, and if possible check that the file contents are OK.You shouldn’t really see any files with the `D’ attribute unless either those files are being used, or your filesystem is chock full. Do `df’ to check that the filesystem isn’t full, then repeat the find command. If you still have D files, then worry a little….
  2. Save the attributes from all your existing files.This can be done by using the special version of find below, like so: find mountpoints -xdev \\( -type f -o -type d \) \\! -attr ” \-printf ‘=%E\0-m\0%M\0-b\0%B\0%p\0’ |gzip -9 > filename.gz
  3. Do one of the following (in decreasing order of preference, though I suspect increasing order of likelihood):If you have plenty of space on your hard drive (enough that you can decompress everything), do: find mountpoints -xdev \-type f -links 1 -attr +cBEXD -print0 |xargs -0 e2decompress;find mountpoints -xdev \\( -type f -o -type d \) -print0 |xargs -0 chattr -cIf you have a good backup system, then just do a full backup and either reformat your drive (giving you an opportunity to repartition) or just remove sufficient files to enable you to do: find mountpoints -xdev \\( -type f -o -type d \) -print0 |xargs -0 chattr -cand still have room over.People with neither an appropriate backup medium nor sufficient space to do `chattr -c -R /’ can use tar and its –remove-files option.
  4. Once under 0.4, put compressed attributes on all directories (to give you enough space to restore your archived files), like so: find mountpoints -type d -print0 | \xargs -0 chattr +c -m method -b clustersizethen extract all your archived files, then remove all the compressed attributes from the directories, like so: find mountpoints -type d -print0 | \xargs -0 chattr -cthen restore the attributes by doing: xargs -0 -n 6 chattr -V < filename.gz

Here’s the find code:

findutils-e2c_4.1.4-34.4_i386.deb: Debian i386 package (glibc2.1binaries).

e2cfindutils_4.1.4.orig.tar.gz: source (with changes for e2comprbut not Debian).

e2cfindutils_4.1.4-34.4.diff.gz: Debian diffs (frome2cfindutils_4.1.4.orig).

e2cfindutils-4-patch-4.1.gz: e2compr diffs (from standard findutils-4.1). Useful only if you already have the non-e2compr findutils source.

See Installing for instructionsparticular to your distribution (including how to useapt-get if you use Debian).

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e2compr maintainersLast modified: Fri Nov 12 13:07:23 EST 1999

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