Re: [gentoo-user] Re: Suggestions for backup scheme?

[Rich Freeman <rich0@gentoo.org>]

On Wed, Jan 31, 2024 at 12:40 PM Thelma <thelma@sys-concept.com> wrote:
>
> If zfs file system is superior to ext4 and it seems to it is.
> Why hasn't it been adopted more widely in Linux?
>

The main barrier is that its license isn't GPL-compatible.  It is
FOSS, but the license was basically designed to keep it from being
incorporated into the mainline kernel.

The odd thing is that right now Oracle controls both ZFS and btrfs,
with the latter doing mostly the same thing and being GPL-compatible,
but it hasn't tended to be as stable.  So we're in a really long
transitional period to btrfs becoming as reliable.

ZFS also cannot be shrunk as easily.  I think that is something that
has been improved more recently, but I'm not certain of the state of
it.  Also, bootloaders like grub aren't 100% compatible with all of
its later features, and it isn't even clear in the docs which ones are
and aren't supported.  So it doesn't hurt to keep /boot off of zfs.

I'm sure ext4 also performs better.  It has to be faster to just
overwrite a block in place than to remap the extents around the
change, even if the latter is safer.  I'd expect zfs to outperform
ext4 with full data journaling though, which would have a comparable
level of safety, assuming it isn't on RAID.  I don't think there are
any RAID implementations that do full write journaling to protect
against the write hole problem, but those would obviously underperform
zfs as well.

-- 
Rich