:: Re: [DNG] backups from ext4 to ntfs…
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Author: Rick Moen
To: dng
Subject: Re: [DNG] backups from ext4 to ntfs - extended attributes and access control lists
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.)