[Voyage-linux] Re: Question about copying Voyage installation on CFs

Thu Oct 13 11:03:42 HKT 2011

I have recently gotten back to making Voyage USB drive systems. We use these
for network testing, most often iperf with tcpdump and analysis. It is very
useful to have a modifiable system so I am not using squeezefs, but I would
also like to make the images as small as possible for transfer over WAN
links.

So, I have a 1 GB USB drive as the master, and a compressed image was 600
MB. This week I reduced that to 200 MB by making a large zero filled file in
all of the empty disk space and then deleting it before doing the dd image
copy and gzipping. 700 MB of zeros compresses a lot better than random bits!

Tonight I successfully used gpartd to expand the file system after the 1 GB
image was copied to a 4 GB USB flash drive.

Jon

2011/10/12 <jfh at greenhousepc.com>

> Greets,
>
> Thanks for sharing this -- any tips that can help people deploy Voyage are
> helpful.
>
> I use a similar process to what you described -- I keep an old MBR lying
> around (heh) with a partition table that I just so happen to like.  When I
> create the first partition, I create the partition with the target size,
> then the rest of the partitions (I have a VERY small swap whose sole purpose
> is to prevent crashes -- the total swap traffic is non-existent, and when
> the systems swap, I find out why and fix that).  THEN I go back and delete
> the root partition and make it a small size -- I'm up to 640MB right now.  I
> then DD in the root image I have, all 620 or 630MB of data.
>
> Once the root partition has been imaged this way, I go back, delete the
> first partition a second time, then expand it to fit all the space it fit
> before.  Why do it this way?  Because this way I know when the image file is
> too large -- it's a check for the DD that I use to image that partition.
> Also, if I need to capture the partition image, the partition is still only
> 640MB and I'm not stuck playing games to trim it down.
>
> With the root partition back to the size I want, I can now expand the
> filesystem to fit all available space.
> --
> Julie Haugh
> Senior Design Engineer
> greenHouse Computers, LLC // jfh at greenhousepc.com // greenHousePC on
> Skype
>
>
>  -------- Original Message --------
> Subject: [Voyage-linux] Re: Question about copying Voyage installation
> on CFs
> From: Gustin Johnson <gustin at meganerd.ca>
> Date: Wed, October 12, 2011 4:19 pm
> To: Emilio Arrufat <emilio at lagalera.org>
> Cc: voyage linux Mailing List <Voyage-linux at voyage.hk>
>
>
> Also CC'ing the list as this may be useful to some.
>
> The procedure that you listed should have worked if you had
> partitioned the new CF card first.
>
> The first 512 bytes of a disk contain the MBR (Master Boot Record) and
> partition table. The first 446 bytes contain the MBR while the rest
> is the partition table.
>
> If you want the process to be repeatable what I would suggest is to
> make your primary partition significantly less (say 50 megabytes or so
> to be safe) than the smallest card you are likely to use. Around here
> I cannot buy anything smaller than a 4 GB CF card so I make my system
> images ~3.9 GB.
>
> At this point there are a couple of slightly different ways to go.
>
> First, you could backup the original card as you described below.
> Then you partition the new card with fdisk/cfdisk/parted etc. You
> then restore the MBR to the major device name (eg. /dev/sdc) inverting
> the command you used to backup the MBR. You then restore the
> partition back to the minor device name (eg. /dev/sdc1). At this
> point you should be good to go.
>
> The second choice is to simply ddrescue one card over to the other.
> If the destination is slightly smaller you may have to repair the
> partition table but you should still be able to boot off the imaged
> device.
>
> If you do this often enough, something like FOG might be useful to
> image these systems with. We used to do this but we now deploy so few
> that we just build again from scratch using the latest version of
> voyage. We do very little customization as we use the Alix SBCs as
> network appliances, so things like the firewall, traffic shaping, and
> multipath routing take minutes to install (just bash scripts that we
> put in /usr/local/ with symlinks to /etc/init.d) and usually
> everything else we need is already on the system.
>
> Hope this helps!
>
> On Tue, Oct 11, 2011 at 4:33 PM, Emilio Arrufat <emilio at lagalera.org>
> wrote:
> > Dear Gustin,
> > my name is Emilio Arrufat, from Spain. I would apologize for any
> > inconvenience for sending to you this message, but I would want to ask
> > you about a procedure you wrote I have found on internet about
> > duplicating Voyage in CF cards of different sizes.
> >
> > It solves many problems I was wondering about, in particular when I
> > tried to duplicate a whole, say 1GB, card to another 1GB one I found
> > what you mentioned: "If you want to backup the whole drive and you are
> > sure that the drives are exactly the same (even though they are both 8
> > GB, they may not be exactly the same, down to the last byte), I
> > usually just use ddrescue." My cards had different geometry and
> > duplication did not work. So when I read from you "What I do is backup
> > the MBR and partitions separately. " it sounded to me as my solution.
> >
> > However I have tried several times with no luck. Let me tell what I
> > did and ask you if you can give me any advice:
> >
> > say my CF is /dev/sdc. First of all I formatted the first card with a
> > size slightly minor than 1GB, not ocuppying the whole card, to avoid
> > restoring on cards with a few less capacity. Installed Voyage and test
> > it.
> >
> > Second I follow your procedure: 1) backed up the card MBR:  dd
> > if=/dev/sdc of=/path/to/alix.MBR.img count=1 bs=446  and 2) backed up
> > the partition where Voyage is installed:  ddrescue /dev/sdc1
> > /path/to/alix.sda1.img
> >
> > Third: I partitioned the second card with a partition expanding to the
> > whole capacity (hope bigger size than first card) and restored the
> > MBR: dd if=/path/to/alix.MBR.img of=/dev/sdc count=1 bs=446 and the
> > partition of Voyage: ddrescue /path/to/alix.sda1.img /dev/sdc1
> >
> > The restoring ended with no errors, but the OS does not boot up. I
> > have tested it several times.
> >
> > Do you have any clue?
> >
> > I would appreciate your help,
> >
> > thanks in advance,
> >
> > Emilio Arrufat
> >
>
> _______________________________________________
> Voyage-linux mailing list
> Voyage-linux at list.voyage.hk
> http://list.voyage.hk/mailman/listinfo/voyage-linux
>
>
> _______________________________________________
> Voyage-linux mailing list
> Voyage-linux at list.voyage.hk
> http://list.voyage.hk/mailman/listinfo/voyage-linux
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.voyage.hk/pipermail/voyage-linux/attachments/20111012/a13edbd1/attachment.html>