From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54020) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkaK8-0001yZ-9G for qemu-devel@nongnu.org; Fri, 09 Oct 2015 12:15:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZkaK4-0003j0-Es for qemu-devel@nongnu.org; Fri, 09 Oct 2015 12:15:12 -0400 References: <1442907862-21376-1-git-send-email-wency@cn.fujitsu.com> <1442907862-21376-4-git-send-email-wency@cn.fujitsu.com> <56157599.9020608@redhat.com> <87vbahq41u.fsf@blackfin.pond.sub.org> From: Max Reitz Message-ID: <5617E7FF.7020405@redhat.com> Date: Fri, 9 Oct 2015 18:14:55 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2E8q4xxBbhQDd7d5GC5kESr06Bfnc3INp" Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v5 3/4] qmp: add monitor command to add/remove a child List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alberto Garcia , Markus Armbruster Cc: Kevin Wolf , Yang Hongyang , zhanghailiang , Jiang Yunhong , Dong Eddie , qemu devel , "Dr. David Alan Gilbert" , Gonglei , Stefan Hajnoczi , qemu block This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --2E8q4xxBbhQDd7d5GC5kESr06Bfnc3INp Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 08.10.2015 10:29, Alberto Garcia wrote: > On Thu 08 Oct 2015 08:15:25 AM CEST, Markus Armbruster wrote: >>> For the second point, you should also consider how useful this >>> feature is to management tools. Just being able to remove and attach >>> children from a quorum node seems very useful on its own. I don't see= >>> why we should wait for having support for other block drivers; also, >>> for most block drivers there is no meaningful way of adding or >>> removing children as nicely as that is possible for quorum. >> >> Okay, this is an argument I might be able to buy. >=20 > Note that if we want to make this interface stable there's one use case= > missing: there's currently no way to change the vote threshold. Besides what Kevin said: If you add a new function, that would be independent from these two functions. If want to add it as an optional parameter to blockdev-add-child so the change is done atomically, that wouldn't be an incompatible interface change either. Max > This is maybe not so important for the COLO use case, but for the > general case of adding and removing children from a quorum node having > the possibility to change the threshold makes a lot of sense. >=20 > That would probably require a its own API ('quorum-set-threshold' or > something like that) so I don't think it has an effect on these > child-add and child-del commands, but I wanted to mention it here anywa= y > in case someone sees something that I'm overlooking. >=20 > Berto >=20 --2E8q4xxBbhQDd7d5GC5kESr06Bfnc3INp Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJWF+f/AAoJEDuxQgLoOKytgFgIAIjgyH4+Ls01glCyRbcUUDhD wcxmtQ1/D1OHiJlbHwdMcEYD24zy0dPctC3IQso0vNQ/rm+dZE0xQFTDsJwpaQzf 6UV7+c0eE6M8OqRGh0KWQwtu48ohkyqCy7kRmiSWya7U7/fe3eU6sfZsL8vrK2+L LGvU7PIO0exstZbcPtMD6GJGkT7pll1VJ3uTa7CD2eRxLxXKeB6JAyNrKkLF0B4X AxxlAku90luQlL5J7R8Aw5rM0sKUohLWH5nTzJTA3g4m3BrCFtmvjVULFd3phZ1y Qks1u29uQyVWlSj9fOOAUnePnM6TjpKPwOTdJlMC8xJweAB9qjskC6ILP6CM1CQ= =raPE -----END PGP SIGNATURE----- --2E8q4xxBbhQDd7d5GC5kESr06Bfnc3INp--