From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.com>
Subject: Re: [PATCH] Since changing number of devices in RAID10 is possible fix man and add a test (RFC)
Date: Mon, 05 Feb 2018 06:58:22 +1100
Message-ID: <87lgg8plwh.fsf@notabene.neil.brown.name>
References: <20180203170006.5750-1-a3at.mail@gmail.com>
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On Sat, Feb 03 2018, Azat Khuzhin wrote:

> It requires patch from, otherwise it fails anyway:
>   "mdadm/grow: adding a test to ensure resize was required"
>   https://www.spinics.net/lists/raid/msg59743.html
>
> Since: 19ceb16dafb7df98ff90298008d4488dc93b370a ("Grow: add raid10
> reshape.") # mdadm mdadm-3.2.5-120-g19ceb16
> Since: 3ea7daa5d7fde47cd41f4d56c2deb949114da9d6 ("md/raid10: add reshape
> support")  # linux v3.4-rc5-15-g3ea7daa5d7fd
> Tested-on: linux 4.13+
>
> Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
> Cc: NeilBrown <neilb@suse.com>
> Cc: Zhilong Liu <zlliu@suse.com>
> ---
> Any thoughts?

I think this is mostly good - thanks.

The man page should mention that change the number of devices
isn't supported for 'far' layouts, and the test code should check that
it works for 'offset' layouts.

It wouldn't hurt for the test code to also test that the number of
devices can be reduced.

Thanks,
NeilBrown


>
>  mdadm.8.in      |  2 +-
>  tests/02r10grow | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+), 1 deletion(-)
>  create mode 100644 tests/02r10grow
>
> diff --git a/mdadm.8.in b/mdadm.8.in
> index f0fd1fc..62da7b1 100644
> --- a/mdadm.8.in
> +++ b/mdadm.8.in
> @@ -123,7 +123,7 @@ missing, spare, or failed drives, so there is nothing=
 to monitor.
>  Grow (or shrink) an array, or otherwise reshape it in some way.
>  Currently supported growth options including changing the active size
>  of component devices and changing the number of active devices in
> -Linear and RAID levels 0/1/4/5/6,
> +Linear and RAID levels 0/1/4/5/6/10,
>  changing the RAID level between 0, 1, 5, and 6, and between 0 and 10,
>  changing the chunk size and layout for RAID 0,4,5,6,10 as well as adding=
 or
>  removing a write-intent bitmap and changing the array's consistency poli=
cy.
> diff --git a/tests/02r10grow b/tests/02r10grow
> new file mode 100644
> index 0000000..0b177fe
> --- /dev/null
> +++ b/tests/02r10grow
> @@ -0,0 +1,32 @@
> +
> +# create a 4-disk raid10 array, make it 8-disk array.
> +#
> +# This SHOULD fail:
> +# - before mdadm 3.3 and linux 3.5
> +# - with metadata v0.90
> +#
> +# This also fails:
> +# - with metadata 1.0 with "mdadm: Insufficient head-space for reshape o=
n /dev/loop1" error
> +
> +m=3D2
> +cm=3D1
> +
> +for metadata in 1.1 1.2; do
> +    # 4 disks
> +    mdadm -CR $md0 --metadata $metadata --level raid10 --raid-disks 4 $d=
ev1 $dev2 $dev3 $dev4
> +    check wait
> +    check state UUUU
> +    check raid10
> +    testdev $md0 $m $mdsize1 $[512*cm]
> +
> +    # 8 disks
> +    mdadm $md0 --add $dev8 $dev9 $dev10 $dev11
> +    mdadm $md0 --grow --raid-devices 8
> +    check wait
> +    check state UUUUUUUU
> +    check raid10
> +    testdev $md0 $m $[mdsize1*2] $[512*cm]
> +
> +
> +    mdadm -S $md0
> +done
> --=20
> 2.16.1

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