From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: How do I set 'write-behind' on existing array? Date: Tue, 21 Oct 2014 08:14:29 +1100 Message-ID: <20141021081429.509f2d72@notabene.brown> References: <5445011B.8040008@hanswkraus.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/qv=uI.5YYX7GRADurke5fAZ"; protocol="application/pgp-signature" Return-path: In-Reply-To: <5445011B.8040008@hanswkraus.com> Sender: linux-raid-owner@vger.kernel.org To: Hans Kraus Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/qv=uI.5YYX7GRADurke5fAZ Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 20 Oct 2014 14:33:31 +0200 Hans Kraus wrote: > Hi, >=20 > I want to expand an existing root array with an SSD. For that purpose I > try to set firstly 'write-behind' on that array. Afterwards I will add > the SSD, remove the HDs and re-add them with 'write-mostly'. On that > array is the root filesystem, therefore stopping is no option. In > >/home/kraush/work/mdadm/mdadm< is the latest mdadm version from git. > I tried: > ----------------------------------------------------------------------- > root@elefant:/home/kraush/work/mdadm/mdadm# ./mdadm --manage=20 > --write-behind=3D4096 /dev/md4 > mdadm: :option --write-behind not valid in manage mode > root@elefant:/home/kraush/work/mdadm/mdadm# ./mdadm --grow=20 > --write-behind=3D4096 /dev/md4 > mdadm: no changes to --grow > ----------------------------------------------------------------------- > What is the correct syntax? >=20 Not quite. "write-behind" is a property of the bitmap. To enable write-behind on an array you first need to remove the bitmap if there is one mdadm /dev/md4 --grow --bitmap=3Dnone then add a new bitmap with the required property mdadm /dev/md4 --grow --bitmap=3Dinternal --write-behind=3D4096 NeilBrown --Sig_/qv=uI.5YYX7GRADurke5fAZ Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIVAwUBVEV7NTnsnt1WYoG5AQKZiA/9E+grqpyn8fPuKdWWJUU+4fseYwPS8V1d aX8aeC0tQauy22VnERnjJaGa1kLLJJOkyNbsJgIUnYzOfqviptR77ZTp2GaIr2qr SNEBmAzYb5qU4Uo6d2bb7262cN+kPefrdu+RZQOj8/JBBWwHx/bfK3H+0s1NYaKC RjNAtEgz3FliGoWRvlfmfUh13hJ4UM2ktpupVNU8utlPo5/v++DWdUhV34NIKfMo U/8Gg8C1r/PrhdoOT7eR2CwZPDDtidYGUAFRJUIgBE6NM4AJjiywlC26PsIyRyVK tYatFU7+u9mwlhKYHHTmQIiZ+H9r2I5nk4zh7nc+hTbOkjIG/O7fGm5Ag6+AFoUt IHny+zZ5JJ0wM7g8j7pAo1W6O5c1eCDMxDZSwdvzs2Qr/cSWBXjmfAKB0Nhgmuz6 LHVFlL9z9BTH3l7fZvkUeyHDeDe7Kx+5fEndzgX4cHc7jiettwD1xKKf0kD4xkuz DNXWutKI+Dsi/4GllWXMWLd6wraHm1ghqUo+J7dGW1zlne9ByUbxw67KOjsnkoJX udh15GIx1parCiVHYJbiaUIvgper8jA/F6sQHfVbyODL+m9geOt8f9HUeLGuREZT DLkdJZWORctVgK3qi/vz88imrlMT7j/8zvSDe/dn/S1PeTne2h7LqZQTK1GC13Te a4EfMxWcWpo= =kj14 -----END PGP SIGNATURE----- --Sig_/qv=uI.5YYX7GRADurke5fAZ--