#1992 PR merged: Include UDF support in rescue ISO when backup is stored on the ISO itself

Labels: enhancement, fixed / solved / done

rmetrich opened issue at 2018-12-04 08:46:

Pull Request Details:
  • Type: Bug Fix

  • Impact: High

  • How was this pull request tested?

Tested on x86_64 with xorrisofs (no change) and mkisofs:

  • no change when backup is not embedded
  • udf included + mkisofs option when backup is embedded
  • Brief description of the changes in this pull request:

When using BACKUP_URL=iso:///backup and ISO generator is mkisofs or genisoimage, include the udf module and enable creating an hybrid iso9660/udf DVD.
This is necessary if the backup archive is >= 4GiB, otherwise the following error occurs:

File ./backup/backup.tar.gz is larger than 4GiB-1.
-allow-limited-size was not specified. There is no way do represent this file size. Aborting.

xorrisoifs doesn't require this.

jsmeix commented at 2018-12-04 11:00:

It seems the issue https://github.com/rear/rear/issues/1836
belongs to this pull request.

rmetrich commented at 2018-12-04 11:02:

@jsmeix Indeed, the issue will be solve with this PR.

jsmeix commented at 2018-12-04 11:16:

thank you for this enhancement!

From my point of view it is no bug because it errors out
i.e. the missing functionality is not silently ignored
and the user need to find out later the hardw ay that
his ISO is actually useless.

I think your point in
no change when backup is not embedded
is not correct according to how I understand your code in

# We also include 'udf' module which is required if backup archive is >= 4GiB
# and mkisofs/genisoimage is used.
if $ISO_MKISOFS_BIN --help 2>&1 >/dev/null | grep -qw -- -allow-limited-size ; then
    MODULES+=( udf )
    ISO_MKISOFS_OPTS+=" -allow-limited-size"

because that adds the udf kernel module always when the
ISO_MKISOFS_BIN help output contains -allow-limited-size
which is perfectly o.k. for me, cf.

rmetrich commented at 2018-12-04 11:32:

It's only when sourced by "ISO" method

jsmeix commented at 2018-12-04 11:42:

I meant in case of OUTPUT=ISO the udf kernel module is always added
when the ISO_MKISOFS_BIN help output contains -allow-limited-size
i.e. also when the ISO is less than 4 GiB - but that is perfectly o.k.

jsmeix commented at 2018-12-04 11:43:

if there are no objections I would like to merge it tomorrow.

rmetrich commented at 2018-12-04 11:43:

oh yes, but there is no way to know if mkisofs would fail and rescue iso has already be prepared at the time of the backup creation.
So ISO => udf

jsmeix commented at 2018-12-04 11:57:

only a side note regarding having the needed things in the recovery system
to use ISOs from within the recovery system see
for an example how I was hit by missing "usually expected stuff"
in the currently rather minimal recovery system.

See also
how the recovery system can become a dead end for the user
when not all kernel modules had been included.

Perhaps for ReaR 3.0 we should set in default.conf

MODULES=( 'all_modules' )

jsmeix commented at 2018-12-05 12:52:

many thanks for your enhancement/fix of ReaR!

[Export of Github issue for rear/rear.]