:: Re: [DNG] backups from ext4 to ntfs…
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Author: Bruce Ferrell
To: dng
Subject: Re: [DNG] backups from ext4 to ntfs - extended attributes and access control lists
On 5/28/19 3:53 PM, Rick Moen wrote:
> Quoting Joel Roth via Dng (dng@???):
>> I've been backing up my root ext4 filesystem to ntfs for some time, gettings errors
>> from rsync about failing to copy extended attributes.
>> Will it affect the ability of my devuan OS or any major
>> components to function if I lose extended attributes or ACLs?
> I think there is an excellent chance you'll suffer semantic loss in
> either that area or other types of *ix file metadata, and maybe of
> special file types, maybe even symlinks.[1] Like, have you checked that
> rights and ownership are fully preserved? mtime, ctime, and atime?
> I strongly, strongly doubt that.
> I don't know for certain because, frankly, NTFS is so unpromising a
> target for Linux backups that it never would occur to me to try, except,
> if I were absolutely forced to use NTFS as a target, backing up trees
> inside some container archiving format such as tar or cpio that is
> specifically designed to encapsulate *ix metadata. (And, even then,
> extended file attributes and ACLs are exotic enough that I would test.)
>> One common use seems to be the immutable flag.
> Well, there, you can ask yourself: Do I or any other UID0 user employ
> chattr +i on this system? I greatly doubt that any Devuan package does
> so without sysadmin volition to do so. But, equally, I'd be astonished
> if the immutable flag survives an ordinary transit from ext4 to NTFS and
> back (absent extraordinary workarounds to encapsulate file metadata).
> [1] Last I heard, Microsoft OSes had nothing quite like a symlink, which was
> one reason why Cygwin was a bit of a kludge. (They may have fixed that;
> I wouldn't know, having avoided running their OSes on my _won_ machines
> since Windows for Workground 3.11 in 1992.)
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You *could* make a tarball and copy that to NTFS.  Imperfect but no semantic loss that way