Changing filesystem resize patterns
Changing filesystem resize patterns
Posted May 12, 2022 14:44 UTC (Thu) by Hello71 (guest, #103412)Parent article: Changing filesystem resize patterns
> While the problems have been identified, solutions have not been; he was hoping that attendees had some interesting ideas. One thing that would be useful, Ts'o said, is to have a standard format for large filesystem images that could be inflated onto block devices into the full size of the filesystem. The ext4 developers have been experimenting with using the qcow format; there is a utility in e2fsprogs called e2image that can create these images. They only contain the blocks that are actually used by the filesystem, so they are substantially smaller than the filesystem they will create. The XFS developers have also been looking at xfsdump, since it has some similar capabilities, but for XFS filesystems.
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> When he and Wong were talking, they agreed that some single standard format would be useful. One possibility is qcow, but it is not well-specified and the QEMU developers, who created the qcow format, discourage its use as an interchange format, he said. Perhaps there are others that could be considered, but getting agreement between the various filesystems is important. That would help move away from the idea that dd is the state-of-the-art tool for transferring filesystems.
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> When he and Wong were talking, they agreed that some single standard format would be useful. One possibility is qcow, but it is not well-specified and the QEMU developers, who created the qcow format, discourage its use as an interchange format, he said. Perhaps there are others that could be considered, but getting agreement between the various filesystems is important. That would help move away from the idea that dd is the state-of-the-art tool for transferring filesystems.
why not use tar or cpio? as i see it, the benefits of raw filesystem images are: 1. they can be directly mounted, and 2. they can be installed on a storage device using extremely simple and common programs and algorithms (useful for e.g. minimal recovery environments). if you use qcow or some other custom format, neither of these benefits applies anymore, and you may as well use tar (which is more widely supported than your new format).