5 ms·

Which filesystems support this degree of integrity checking? Presumably ZFS, but what about EXT4/3, ReiserFS, BTRFS, ZFS, NTFS, and FAT32? It would be wonderf

Which filesystems support this degree of integrity checking? Presumably ZFS, but what about EXT4/3, ReiserFS, BTRFS, ZFS, NTFS, and FAT32? It would be wonderful if they all have the feature, but I thought only ZFS was really that paranoid.

willis936 4y ago
ZFS and BTRFS have nice online scrubbing features, but nearly every filesystem these days is journaling, including NTFS and XFS (and its contemporaries). Journaling means every block has a checksum. Sure, FAT32 doesn't have that, but no one should ever have the expectation of data integrity on FAT32. You can run checkdisk on journaling filesystems to scrub for errors.
- shakna 4y ago
  FAT is a requirement of UEFI though, isn't it? So if you can boot from the drive, you can't rely on it to have the filesystem integrity preserved at the disk level.
- danachow 4y ago
  > Journaling means every block has a checksum. No it doesn’t. Many journal filesystems use a checksum for log entries, but that is certainly not covering every block of the filesystem with a checksum. And that checksum only comes into play during log recoveries. Once a block is committed to disk there is no checksum in play (unless the fs has special support for it). Some newer journaling filesystems support metadata checksumming, but that is not some requirement to be journaling. XFS has not always supported metadata checksumming, and it’s a relatively recent addition to ext4 (like last decade). NTFS doesn’t do checksums on even metadata. This is one reason why ReFS is a thing.
- wang_li 4y ago
  Journaling means that there is a two phase commit to the metadata of the file system. This helps avoid file system corruption on unclean shutdown and speed up recovery after an unclean shutdown. But it has nothing to do with data checksums. You can’t perform any scrub like behavior to validate your on, e.g., ext4 just because it has a journal.

willis936 4y ago

ZFS and BTRFS have nice online scrubbing features, but nearly every filesystem these days is journaling, including NTFS and XFS (and its contemporaries). Journaling means every block has a checksum. Sure, FAT32 doesn't have that, but no one should ever have the expectation of data integrity on FAT32. You can run checkdisk on journaling filesystems to scrub for errors.

shakna 4y ago
FAT is a requirement of UEFI though, isn't it? So if you can boot from the drive, you can't rely on it to have the filesystem integrity preserved at the disk level.
danachow 4y ago
> Journaling means every block has a checksum. No it doesn’t. Many journal filesystems use a checksum for log entries, but that is certainly not covering every block of the filesystem with a checksum. And that checksum only comes into play during log recoveries. Once a block is committed to disk there is no checksum in play (unless the fs has special support for it). Some newer journaling filesystems support metadata checksumming, but that is not some requirement to be journaling. XFS has not always supported metadata checksumming, and it’s a relatively recent addition to ext4 (like last decade). NTFS doesn’t do checksums on even metadata. This is one reason why ReFS is a thing.
wang_li 4y ago
Journaling means that there is a two phase commit to the metadata of the file system. This helps avoid file system corruption on unclean shutdown and speed up recovery after an unclean shutdown. But it has nothing to do with data checksums. You can’t perform any scrub like behavior to validate your on, e.g., ext4 just because it has a journal.