[ale] has anyone successfully used RSYNC to....

Ed Cashin ecashin at noserose.net
Fri Mar 2 14:23:26 EST 2012


I've done that, but more often, "NEWdrive" is bigger than "HD1" and
"HD2".  I don't have the exact commands handy, but I can describe
them, and whatever anybody tells you about this, make sure you
actually do the procedure you choose *before* you're forced to.
There's inevitably some learning and tweaking, even if you get recipes
from other people.

So in general, for rsync, I used "-a" plus the option that preserves
sparse files ("-S") and the one ("-H") that preserves hard links, and
often the one ("-c") that uses checksums to ensure data integrity.  Of
course, because rsync works over ssh, it's easiest to keep HD2 in a
separate machine, so that you can rsync over the network.  I use "-x"
to stay on one filesystem instead of going into stuff like /proc.

Some UNTESTED illustrative example commands from memory are below,
assuming the only real filesystems on the localhost are / and /home.

  rsync -avSHx / otherhost:/backup-of-hd1
  rsync -avSHx /home/ otherhost:/backup-of-hd1/home

The most tricky thing about rsync is probably that trailing slash in
the second command.  It means "the contents of".  Without it, rsync
would make a new directory called "home" inside /backup-of-hd1/home on
otherhost.

For the boot sector, I would copy it to a local file before the rsync
with dd.  But I no longer think that's as good as getting very
comfortable with the installation of a boot loader like grub or lilo.
There's rarely information in the boot sector that cannot be replaced
with something just as good when you're moving onto NEWdrive.  Most of
the time you can live boot a CD and run grub or something to install
the boot loader in the MBR of NEWdrive.

For the partition table, I used to use sfdisk to dump the partition
info to a format that sfdisk can read to recreate the same
partitioning scheme.  Now I don't think that's necessary either,
because if you're doing a high-level file-based backup like rsync
does, you can just partition NEWdrive however you want, and it's
probably going to be bigger anyway, so good.  And maybe you've learned
something and NEWdrive will have a better partitioning scheme than HD1
did.

For formatting, I think you mean filesystem creation.  In that case,
again, maybe there's a better choice for the filesystem on NEWdrive
than the one you were using on HD1, so it depends.  Because the backup
is at the file level, you can choose whichever filesystem is best for
your needs.  For example, maybe you have 3 partitions on MYNEWDRIVE
and want ext3, so you could do something like "mkfs -t ext3
/dev/MYNEWDRIVE1" and "mkswap /dev/MYNEWDRIVE2" and "mkfs -t ext3
/dev/MYNEWDRIVE3".

After that, mount that new filesystem use the same rsync options to
copy the files from the mounted filesystem of HD2 to the new
filesystem on NEWdrive.  Something like this is what you'd do on
"otherhost" after those filesystem creation commands:

  mkdir /mnt/NEWdrive
  mount /dev/MYNEWDRIVE1 /mnt/NEWdrive
  mount /dev/MYNEWDRIVE3 /mnt/NEWdrive/home
  rsync -avSHx --progress /backup-of-hd1/ /mnt/NEWdrive
  vi /mnt/NEWdrive/etc/fstab  # if you've changed the partitioning
scheme or filesystems

These commands are pretty darn close, but they're untested and
provided without warranty.  If anyone sees errors, please chime in.

OP, please practice using them inside virtual machines or something
until you're as comfortable as anyone else if you intend to do this
when other people are counting on it working successfully.

On Fri, Mar 2, 2012 at 1:38 PM, Courtney Thomas
<courtneycthomas at bellsouth.net> wrote:
> ...(1) back up all their filesystems from HD1 to an archive hard drive HD2,
>
> (2) then replaced HD1 with a NEWdrive which was partitioned, labeled and
> formatted exactly duplicating the replaced HD1, and then
>
> (3) RSYNCed the archived files on HD2 to the NEWdrive, with the result that:
>
> the NEWdrive was not only without fault, but that the previous
> functionality
> of HD1 was exactly duplicated ?
>
> If yes to all 3, would anyone care to share
>
> (1) the RSYNC backup command for HD1 -> HD2
> (2) their partition, label and format commands for NEWdrive
> (3) the RSYNC restore command for HD2 -> NEWdrive
>
> This is obviously of overwhelming importance to all and if anyone can
> point to a
> reliable source, or provide it outright themself, for the above sought
> command
> summary, my gratitude would be boundless  :-)
>
> I am aware that rsync, fdisk, e2label and mkfs are all documented commands,
> but a successful usage, as herein outlined, is, at least in my case,
> frustrating
> days away of trial and error, having already wasting such time in
> pursuit of such
> an outcome using 'dump'.
>
> Sincerely,
>
> Courtney
> _______________________________________________
> Ale mailing list
> Ale at ale.org
> http://mail.ale.org/mailman/listinfo/ale
> See JOBS, ANNOUNCE and SCHOOLS lists at
> http://mail.ale.org/mailman/listinfo



-- 
  Ed Cashin <ecashin at noserose.net>
  http://noserose.net/e/
  http://www.coraid.com/



More information about the Ale mailing list