[lustre-discuss] MDT backup using dump

[Dilger, Andreas]

Nathan,
The "dump" tools quite out of date and does not support several of the features that are present in modern ldiskfs, especially since some of those features are not even supported in the upstream e2fsprogs). 

It would not be usable for doing an MDT backup as-is, though conceivably it could be revived if you had an interest in doing so. I could work with you to describe what would need to be done, since I used to use and help develop this tool at one time in the past, but it definitely won't be a short-term undertaking. 

Cheers, Andreas

> On Apr 21, 2016, at 19:37, Dauchy, Nathan (ARC-TNC)[Computer Sciences Corporation] <nathan.dauchy at nasa.gov> wrote:
> 
> Greetings!
> 
> As an alternative to using tar and file level backups (see my posting earlier today), we are investigating options that might allow backups to be completed in a shorter amount of time, yet not consume as much space as a full dd of the device.  In particular, we are considering the "dump" utility.  It has the added benefit of supporting incremental backups that might come in handy.  Package is here:
>    https://sourceforge.net/projects/dump/files/dump/
> The use of "dump" for Lustre was discussed 7 years ago here:
>    http://lustre-discuss.clusterfs.narkive.com/VaGj2667/basic-dump-question-for-lustre-mdt
> And support for ext4 was added to dump/restore in 2009:
>    https://bugs.launchpad.net/ubuntu/+source/dump/+bug/325346
> 
> Has anyone successfully used the "dump" approach in the last few years with recent Lustre versions?
> 
> Our current platform is based on CentOS-6.7 and lustre-2.5.3.  The stock OS version of dump doesn't seem to understand ext4/ldiskfs... and I ran into problems building the latest dump from source as follows:
> 
> # lvcreate -l95%FREE -s -p r -n mdt_snap /dev/mapper/nbptest--vg-mdttest
> # blockdev --setro /dev/mapper/nbptest--vg-mdt_snap
> # mount -t ldiskfs -o ro,noload /dev/mapper/nbptest--vg-mdt_snap /mnt/snap
> # dump -0uf /tmp/mdt_backup/mdt_backup.dump /mnt/snap
>  DUMP: Date of this level 0 dump: Tue Apr 19 16:20:07 2016
>  DUMP: Dumping /dev/mapper/nbptest--vg-mdt_snap (/mnt/snap) to /tmp/mdt_backup/mdt_backup.dump
>  DUMP: Unsupported feature(s) 0x1000 in filesystem
> /dev/mapper/nbptest--vg-mdt_snap: Filesystem has unsupported feature(s) while opening filesystem
>  DUMP: The ENTIRE dump is aborted.
> 
> # cd /tmp/dump-0.4b44
> # make
> ...
> traverse.c: In function 'convert_dir':
> traverse.c:1061: error: invalid type argument of '->' (have 'int')
> traverse.c:1061: warning: passing argument 1 of 'ext2_get_dirent_size' makes pointer from integer without a cast
> /usr/include/ext2fs/ext2_fs.h:885: note: expected 'struct ext2_dir_entry *' but argument is of type 'int'
> make[1]: *** [traverse.o] Error 1
> make[1]: Leaving directory `/tmp/dump-0.4b44/dump'
> make: *** [all] Error 1
> 
> # rpm -qf /usr/include/ext2fs/ext2_fs.h
> e2fsprogs-devel-1.42.13.wc4-7.el6.x86_64
>  (most current e2fsprogs available from https://downloads.hpdd.intel.com/public/e2fsprogs/)
> 
> Has ldiskfs diverged such that this a bad path to go down?  (last release of dump was back in 2011)
> Is there a simple fix in there somewhere that I'm missing?
> 
> All suggestions are much appreciated!
> 
> Thanks,
> Nathan
> 
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