[dundee] filesystem files

[Nistur]

Thanks for the reply. I hadn't really looked into compression all that much,
I guess I'll use gzip then :)

On 9/14/07, Lee Hughes <toxicnaan at yahoo.co.uk> wrote:
>
> an interesting email?
>
>
> *Nistur <nistur at googlemail.com>* wrote:
>
> I was having a chat last night at the counting house and rememebred
> something I was fiddling around with a few months ago but never got sorted.
>
> >> Okay..
>
> I have a Windows Mobile based phone. I have 2x 2GB SD cards. I have an SD
> card reader on my laptop. I have 1.4GB mini DVD-Rs
>
> >>OKay
>
> Basically, I was wondering if there was any way to back up the SD cards
> into a single file archive, but with no compression. I never use more than
> 1.4GB on any card
>
> okay >> if you don't use more the 1.4GB on a card,
> then you can backup without compression. however
> if you use dd, then it will backup at the block level,
> so it will actually copy empty space too!, so
> you got a few options.
>
> 1. Create a 600MB file of 'zero bytes)...
> then to backup do dd=if=/dev/yousdcard - | gzip > mybackup
>
> you should get a file smaller than 1.4GB
>
> if you get larger than 1.4GB, you could always split in into two 1GB
> images???
>
> I don't think you can use sparse files either, as you
> just doing an image.
>
> you should be able to mount this if it is a sane
> file system.
>
> just do
>
> then to backup do dd=if=/dev/yousdcard of=mybackup
>
> something like.
>
> mount myback /mountpoint -t auto -o loop
>
> should be able to mount it!! if it's fat 32...
>
> obviiosuly just reverse the dd if you want to put it back
> this maybe be slow!!!! be aware the sd cards have a limited write
> capacity, so very time you swap data, you
> lowering the lifetime of your sdcard. it may prove better
> to rsync if bits of your sd card don't change.
>
>
> , but would like to have more than 2 options, say 1 for music, one with
> photos, one with graphics applications, one with emulators and roms etc. In
> the end I would like to automate it so I can switch the contents of the
> cards, with a shell script for example.
>
> >>that should be easy.
>
> I was kinda hoping dd would give me an option to only copy until the
> partition went blank.
> The reason for me not wanting any compression is mainly the photos, the
> camera on it is crap, but of some use anyway, however if I keep compressing
> and uncompressing over and over again, I'm eventually going to end up with
> every file being one large pixel.
>
> >> what are you going on about? I think you need to
> lookup the difference between lossy and unlossy compression systems. gzip
> never looses data bits
> I think you have you knicker in a twist over this.
>
>
>
> On a similar note, is it possible to create a filesystem within a file and
> mount it with -o loop but not have to set the file size before. I have
> managed to create a 4GB ext3 file but was wondering whether it would be
> possible to have one with a variable size, the more you put in it, the
> bigger it got kinda thing.
>
> >> yeah, you need to create a sparse file, sparse files
> can be any size, but unix only allocates real blocks on
> disk when you write to them do a search for sparse files unix dd and you
> should get results.
>
>
>
>
> Thanks in advance
>
> no thank you...
>
> Nistur
>
> >>it's lee actually.
>
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