Michael Shell wrote:
I am interested in how to best create images of filesystems other than ISO on Unix based systems. ISO has a lot of eccentricities (Rock Ridge, Joliet, filename/path-depth restrictions, etc.) that demand a complex custom application (mkisofs) to properly create. However, things should be much more straightforward with UDF (the suggested filesystem for DVDs) as well as for the other filesystem types that have in-kernel read+write support. Building UDF images was discussed in a very informative post by Tony Caola in September 2003: http://lists.debian.org/cdwrite/2003/09/msg00013.html
Tony's procedure is basically to create a zeroed file of size equal to that of the target media, create a filesystem within this file via mkudffs, mount it using -o loop, and then copy the desired files into this mounted image. Volker Kuhlmann responded to this idea with http://lists.debian.org/cdwrite/2003/09/msg00014.html in which he stated that UDF support under Linux was a tad buggy as well as lacking many tools that are available for ext2 (e.g., resize2fs).
All of this brings some questions to mind.
1. Have the bugs Volker encountered with UDF been fixed now? Volker,
what versions of kernel and udftools were buggy for you?
2. How does UDF fare as far as faithfully preserving all the ext2
attributes (uids, permissions, hard/soft links, pathname lengths,
etc.)?
3. How exactly are we supposed to determine/control the size of the filesystem and image file? (a) Is there a table/chart that shows the number of blocks of all the common optical media (74min CD, 80min CD, 4.7GB DVD, etc.) or is there some way we can get this from the /dev (loaded with "blank" media) itself?
(b) The ISO filesystem seems not to have a problem with image files that are smaller than the target media. Is this true with UDF and ext2 as well? (The answer might seem to be an obvious "yes", but I don't want to assume that the image file size is identical to the concept of a partition.)
(c) If so, how do we best go about resizing the filesystem as well as its containing image file to match the actual storage requirements of the files to be archived? (So that our .img files can be smaller than the target media if we don't fill it all.) IMHO, it seems to me that the minute "mount -o loop" became possible under Linux, we should have had the tools to manage filesystem and image file sizes for all of the supported filesystem types.
Of course, I am sure things get a lot more complicated by the filesystem "growing" or appending required for multisession recording of nonrewritable media. UDF may allow for a "growudffs" approach, but I doubt if ext2 can.
Sure, make a big empty file, do a mke2fs, making the block size 4k, then mount it. Copy anything you want to it, and unmount it. Now burn it to a CD (or DVD). Easy as that.
-- bill davidsen <[EMAIL PROTECTED]> CTO TMR Associates, Inc Doing interesting things with small computers since 1979
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