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"William L. Maltby" 06-25-2008 07:48 PM

backup with dd
 
On Wed, 2008-06-25 at 12:07 -0700, John R Pierce wrote:
><snip>

> i've generally used dump(8) and restore(8) to image ext2/3FS....
> this can even be used to do an incremental dump although I rarely do that.
>
> while i've never tried this, in theory, if you're using LVM, you can
> snapshot a live filesystem, then dump the unmounted snapshot to get a
> clean image.

?? I've not done it for awhile, but I believe that the snapshot is taken
with the snapshot volume (the LVM snapshot volume, that is) mounted.
I've still got some scripts lying around that do this. The LVM snapshot
volume is not a complete snapshot.

Please correct me if I'm wrong.

If you meant the *resulting* snapshot produced by using the snapshot
facilities, I apologize for wasting your time and bandwidth.

>
> note that snapshotting a database is a somewhat dicey proposition,
> however. I generally prefer to use the databases own dump facility
> rather than backing up its raw tablespace files (pg_dumpall for
> postgres, etc).
> <snip sig stuff>

--
Bill

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"Lanny Marcus" 06-25-2008 08:38 PM

backup with dd
 
On Wed, Jun 25, 2008 at 1:46 PM, Les Mikesell <lesmikesell@gmail.com> wrote:

Hiep Nguyen wrote:


hi all,



i have a centos box and would like to back up just in case the hard drive fail. *one way to do this is duplicate the image of the hard drive, so if the hard drive fail, just remove it and put mirrored hard drive and done.




here my system info:



uname -a

Linux jadenet.jadesterling.com 2.6.9-22.0.2.EL #1 Tue Jan 17 06:51:40 CST 2006 i686 i686 i386 GNU/Linux



df -h

Filesystem * * * * * *Size *Used Avail Use% Mounted on

/dev/mapper/VolGroup00-LogVol00

* * * * * * * * * * * 37G * 15G * 20G *43% /

/dev/hda1 * * * * * * *99M *8.9M * 85M *10% /boot

none * * * * * * * * *188M * * 0 *188M * 0% /dev/shm





i'm looking into dd, but is there anything better than dd?



by the way, i would like to use external hard drive via usb to do mirror image.




dd has the advantage of creating a disk that is instantly usable. *The disadvantages are that you have to have it unmounted while making the copy (boot from a CD) and it takes a long time to complete since you have to copy even the unused blocks. *There is also the possibility that your working disk will develop a bad spot that you don't realize until you hit it during the copy, leaving you with 2 bad disks (rotating 2 copies would avoid this issue).




Clonezilla-live is a boot-from CD linux that will copy just the used portions of the disk and can save to another disk or image files on local disks or over the network. *I'd recommend it over dd, but maybe someone has a way to do LVM snapshots so the copy can be done without a reboot.

I'm downloading the .iso for clonezilla-live now. It's a very small download. 81.2 MB

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Hiep Nguyen 06-27-2008 01:31 PM

backup with dd
 
On Wed, 25 Jun 2008, Lanny Marcus wrote:


On Wed, Jun 25, 2008 at 1:46 PM, Les Mikesell <lesmikesell@gmail.com> wrote:


Hiep Nguyen wrote:


hi all,

i have a centos box and would like to back up just in case the hard drive
fail. one way to do this is duplicate the image of the hard drive, so if
the hard drive fail, just remove it and put mirrored hard drive and done.

here my system info:

uname -a
Linux jadenet.jadesterling.com 2.6.9-22.0.2.EL #1 Tue Jan 17 06:51:40 CST
2006 i686 i686 i386 GNU/Linux

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
37G 15G 20G 43% /
/dev/hda1 99M 8.9M 85M 10% /boot
none 188M 0 188M 0% /dev/shm


i'm looking into dd, but is there anything better than dd?

by the way, i would like to use external hard drive via usb to do mirror
image.



dd has the advantage of creating a disk that is instantly usable. The
disadvantages are that you have to have it unmounted while making the copy
(boot from a CD) and it takes a long time to complete since you have to copy
even the unused blocks. There is also the possibility that your working
disk will develop a bad spot that you don't realize until you hit it during
the copy, leaving you with 2 bad disks (rotating 2 copies would avoid this
issue).

Clonezilla-live is a boot-from CD linux that will copy just the used
portions of the disk and can save to another disk or image files on local
disks or over the network. I'd recommend it over dd, but maybe someone has
a way to do LVM snapshots so the copy can be done without a reboot.



I'm downloading the .iso for clonezilla-live now. It's a very small
download. 81.2 MB



i don't know if this is possible, but assume my centos box's motherboard
goes sour, can i just take its hard drive and put on similar pc?


thanks____________________________________________ ___
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CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
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http://lists.centos.org/mailman/listinfo/centos

Les Mikesell 06-27-2008 03:45 PM

backup with dd
 
Hiep Nguyen wrote:

>

Clonezilla-live is a boot-from CD linux that will copy just the used
portions of the disk and can save to another disk or image files on
local
disks or over the network. I'd recommend it over dd, but maybe
someone has

a way to do LVM snapshots so the copy can be done without a reboot.



I'm downloading the .iso for clonezilla-live now. It's a very small
download. 81.2 MB



i don't know if this is possible, but assume my centos box's motherboard
goes sour, can i just take its hard drive and put on similar pc?


The disk is probably the most likely single thing to fail, but within
some constraints you can move the disk around - and the same issues
apply to image copies and backups. The main thing is that the driver
for the disk controller has to be included in the kernel or initrd, so
for example, moving a scsi disk with the boot/root partitions to a
machine with a different controller will be a problem. You can fix this
with some contortions to rebuild the initrd with the right modules from
a rescue mode CD boot. You may also have to reconfigure the display if
you have a different video card or monitor but you can normally run in
text mode while doing that.


--
Les Mikesell
lesmikesell@gmail.com

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