On 2017-03-04 01:12 PM, Craig Barratt wrote:
BackupPC community,
I'm happy to announce that BackupPC 4.0.0 has been released on Github
<https://github.com/backuppc/backuppc/releases> and SourceForge
<https://sourceforge.net/projects/backuppc/files/backuppc/4.0.0/>.
BackupPC 4.0.0 is a significant improvement over 3.x in terms of
performance and storage efficiency. It is backward compatible with 3.x
storage, so it can be used to upgrade an existing V3 installation as
well as for brand new installs.
BackupPC 4.0.0 requires the perl module BackupPC::XS
<https://github.com/backuppc/backuppc-xs/releases> (>= 0.50) and
rsync-bpc <https://github.com/backuppc/rsync-bpc/releases> (>= 3.0.9.5).
After installing those two packages, BackupPC 4.0.0 can be installed
from the tar ball with:
tar zxf BackupPC-4.0.0.tar.gz
cd BackupPC-4.0.0
perl configure.pl <http://configure.pl>
See the README.md, ChangeLog and doc/BackupPC.html
<http://backuppc.sourceforge.net/BackupPC-4.0.0.html> files for more
information. An overview of the major changes is below.
Thanks for to everyone who provided fixes and reported issues with the
alpha and github versions.
Enjoy!!
Craig
Here's a summary of the most significant changes in V4:
* No use of hardlinks (except temporarily to do atomic renames).
Reference counting is handled at the application level in a batch
manner (hardlinks will still remain for any legacy V3 backups).
* Backups are stored as "reverse deltas" - the most recent backup is
always filled and older backups are reconstituted by merging all
the deltas starting with the nearest future filled backup and
working backwards.
* This is the opposite of V3 where incrementals are stored as
"forward deltas" to a prior backup (typically the last full backup
or prior lower-level incremental backup, or the last full in the
case of rsync).
* Since the most recent backup is filled, viewing/restoring that
backup (which is the most common backup used) doesn't require
merging any deltas from other backups.
* The concepts of incr/full backups and unfilled/filled storage are
decoupled. The most recent backup is always filled. By default,
for the remaining backups, full backups are filled and incremental
backups are unfilled, but that is configurable.
* Uses full-file MD5 digests, which are stored in the directory
attrib files. Each backup directory only contains an empty attrib
file whose name includes its own MD5 digest, which is used to look
up the attrib file's contents in the pool. In turn, that file
contains the metadata for every file in that directory, including
each files's MD5 digest.
* The Pool layout still supports chains to handle md5 collisions.
While collisions can be constructed and are now well-known, they
are highly unlikely in the wild. Pool files are never renamed or
moved, unlike V3.
* Any backup can be deleted (deltas are merged into next older
backup if it is not filled).
* The reverse deltas allow "infinite incrementals" - no need for a
full backup if you are willing to trade speed for the risk that a
file change will not be detected if the metadata (eg, mtime or
size) doesn't change.
* An rsync "full" backup now uses --checksum (instead of
--ignore-times), which is much more efficient on the server side -
the server just needs to check the full-file checksum computed by
the client, together with the mtime, nlinks, size attributes, to
see if the file has changed. If you want a more conservative
approach, you can change it back to --ignore-times, which requires
the server to send block checksums to the client.
* The use of rsync --checksum allows BackupPC to guess a potential
match anywhere in the pool, even on a first-time backup. In that
case, the usual rsync block checksums are still exchanged to make
sure the complete file is identical.
* Uses a modified rsync called rsync_bpc (currently based on
rsync-3.0.9) on the server side (in place of File::RsyncP), with a
C code interface to the BackupPC storage. So the whole data path
for rsync is now in compiled C code, which is much faster than perl.
* Due to the use of rsync-3.X, acls and xattrs are supported, and
many other useful options (but not all) are supported. Rsync
protocol 30 supports the efficient incremental file list, which
significantly improves memory usage and startup time. It also
supports MD5 full-file checksums, which match BackupPC's new
digest. That allows a full-file digest to be checked as easily as
an mtime on the server side.
* Significant portions of the BackupPC code are now compiled C code
in a new module called BackupPC::XS that is dynamically linked to
perl.
* V3 migration: nothing specific is needed. V4 can
browse/view/restore V3 backups. When you install V4, no changes
are made to any V3 backups. If you are upgrading from V3, be sure
to set $Conf{PoolV3Enabled} to 1 so the old V3 pool is searched
for matching files.
o When you install V4, it will notice that the V3 pool exists.
Running configure.pl <http://configure.pl> should set
$Conf{PoolV3Enabled} to 1 in that case, but you should be sure
to check that.
o When a V4 backup is first done, BackupPC_backupDuplicate is
run to duplicate the most recent V3 backup to create a new V4
backup. A "filled" view of the most recent V3 backup is used
to create a "filled" V4 backup tree.
o This step could be time consuming, since every file needs to
be read (as a V3 file) and written as a V4 file. However, the
V4 pooling code knows about the V3 pool, so it will move the
V3 pool file into the V4 pool. So this duplication process
doesn't burn a lot of pool storage space, but every file still
needs to be read (to compute the MD5 digest) and "written"
(really just matching/linking).
o Expiry: all the V3 + V4 backups are considered on a combined
basis for expiry checking.
o On a clean new V4 install, the steps of computing and checking
V3 digests is eliminated.
--
This is great news. Now to figure out how to upgrade my Ubuntu 14.04 box.
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