Gus,
Thank you for a great answer. I left out the info for a better backups
answer because I am not looking to do backups this way. I am looking to
move the data off a drive I don't trust (occasional errors) to a disk
that I do trust (trust more that the current one anyway).
A customer who chose to use a single disk, is about to go in to
production and the disk, which he has put much labor in to configs, is
spitting occasional errors. Just wanted to give him a boost in
reliability of I can... no provide backups for the whole drive on an
ongoing basis.
Thanks,
Mike
On Sun, 2007-08-05 at 12:05 -0700, Gus Wirth wrote:
> Michael J McCafferty wrote:
> > All,
> > I have a customer who has a lot of time invested in configuring his
> > system and is ready to put it in to production. However, we are getting
> > some disk errors on occasion and it's tough to trust it for the long
> > haul. What is the hot ticket for putting the exact same thing on another
> > drive. It's easy to have another identical server sitting next to it at
> > the same time, or put an identical disk in the same system to copy stuff
> > over.
> >
> > I am sure I could spend the time to do dd and fdisk, etc, but dumb it
> > down and speed it up for me. :o) Hmm... can I put a second disk in the
> > system and do a dd if=/dev/hda of=/dev/hdb and will that get the boot
> > sectors, etc ? Is it that simple ?
>
> Yes, it is that simple. That's how I back up my home system. Although I
> would put the second/backup drive on a different controller for
> simplicity and performance reasons. Here's how I do it:
>
> Main disk is attached as primary master /dev/hda in a removable drive
> rack (Lian Li RH-40 if you want to know)
>
> Backup disk is in a removable drive rack (same as primary) on secondary
> master /dev/hdc [1]. The backup disk preferably should be identical to
> the main disk but can be bigger. Logical Block Addressing (LBA) got rid
> of all the CHS weirdness a long time ago.
>
> Since both drives are jumpered as master it's trivial to swap drives
> because they are both in the same rack type and configuration. As an
> alternative you could put the backup drive in an external USB or
> Firewire box. Modify the below instructions accordingly.
>
> Boot the system with your favorite rescue CD that will recognize the
> drives and their controllers and also has the dd command. Mine happens
> to be Knoppix.
>
> Either become root or use sudo the following:
>
> $ sudo dd if=/dev/hda of=/dev/hdc bs=1M
>
> WARNING: If you are using Knoppix, make SURE you turn off swap!
> Otherwise it will use the swap on the backup disk, and you will
> overwrite swap that is in use. It WILL crash your session! You also want
> to make sure you turn on DMA because it will seem to take forever for a
> large sized disk without it.
>
> I set the block size to 1 megabyte to ensure the buffers get used. That
> number works well for me.
>
> This will create an exact duplicate of the entire drive when it is
> finished. It takes me about 40 minutes to duplicate a 60GB disk.
>
> Store the backup drive somewhere safe.
>
> If you have data that is changing and you want to synchronize the
> backups, you may be able to use rsync on just the data portion, say
> /home, without having to go through the whole dd cycle. Just plug in the
> disk (if it isn't already connected), mount the appropriate partition,
> and run rsync for that partition/directory.
>
> You left off a lot of required info for a better answer, like how often
> you want backups to happen, whether you can be offline for a period of
> time, who will be making the backups, etc. but hopefully this will give
> you an idea.
>
> Gus
>
> [1] Not really, but this illustrates the point.
>
>
--
************************************************************
Michael J. McCafferty
Principal, Security Engineer
M5 Hosting
http://www.m5hosting.com
You can have your own custom Dedicated Server up and running today !
RedHat Enterprise, CentOS, Fedora, Debian, OpenBSD, FreeBSD, and more
************************************************************
--
[email protected]
http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
