On 2024-05-01 10:50:12 +0200, Ulli Horlacher wrote:
> On Mon 2024-04-29 (12:34), Johannes Thumshirn wrote:
>
> > I have used 2PB filesystems in my RAID Stripe Tree test environment, but
> > for practical uses, I suggest you to enable the block-group tree feature
> > during mkfs time.
>
> I cannot find such an option in man-page for mkfs.btrfs

    $ mkfs.btrfs  -O list-all
    Filesystem features available:
    mixed-bg            - mixed data and metadata block groups (compat=2.6.37, safe=2.6.37)
    quota               - quota support (qgroups) (compat=3.4)
    extref              - increased hardlink limit per file to 65536 (compat=3.7, safe=3.12, default=3.12)
    raid56              - raid56 extended format (compat=3.9)
    skinny-metadata     - reduced-size metadata extent refs (compat=3.10, safe=3.18, default=3.18)
    no-holes            - no explicit hole extents for files (compat=3.14, safe=4.0, default=5.15)
    free-space-tree     - free space tree (space_cache=v2) (compat=4.5, safe=4.9, default=5.15)
    raid1c34            - RAID1 with 3 or 4 copies (compat=5.5)
    zoned               - support zoned devices (compat=5.12)
    block-group-tree    - block group tree to reduce mount time (compat=6.1)

So I believe it would be `mkfs.btrfs -O block-group-tree ...'.

>
>
> --
> Ullrich Horlacher              Server und Virtualisierung
> Rechenzentrum TIK
> Universitaet Stuttgart         E-Mail: horlacher@tik.uni-stuttgart.de
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> 70569 Stuttgart (Germany)      WWW:    https://www.tik.uni-stuttgart.de/
> REF:<6609017e-8931-4559-b613-4b3e28d9fb48@wdc.com>
>

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cache invalidation, naming things and off-by-one errors.