From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45336) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YxCbf-0000bS-4S for qemu-devel@nongnu.org; Tue, 26 May 2015 07:01:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YxCba-0007Nz-5z for qemu-devel@nongnu.org; Tue, 26 May 2015 07:01:11 -0400 Received: from mail-wi0-x22a.google.com ([2a00:1450:400c:c05::22a]:37162) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YxCba-0007Nk-0e for qemu-devel@nongnu.org; Tue, 26 May 2015 07:01:06 -0400 Received: by wifw1 with SMTP id w1so25863742wif.0 for ; Tue, 26 May 2015 04:01:05 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <5564526D.4010001@redhat.com> Date: Tue, 26 May 2015 13:01:01 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <20150523203842.20290.75365.malonedeb@chaenomeles.canonical.com> <20150524075419.20152.84643.malone@chaenomeles.canonical.com> <20150526101805.GG13262@stefanha-thinkpad.redhat.com> In-Reply-To: <20150526101805.GG13262@stefanha-thinkpad.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [Bug 1458239] Re: Use qed instead of qcow2 for "-snapshot" functionality List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , =?UTF-8?B?0JrQvtGA0LXQvdCx0LXRgA==?= =?UTF-8?B?0LMg0JzQsNGA0Lo=?= <1458239@bugs.launchpad.net> Cc: qemu-devel@nongnu.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 26/05/2015 12:18, Stefan Hajnoczi wrote: > On Sun, May 24, 2015 at 07:54:19AM -0000, Коренберг Марк wrote: >> Sorry, I did not know tha qed is just experimental format. I >> thought that qed is successor of qcow2. Can you add some links >> that qcow is not worse than qed ? I did not make any benchmark, >> just read some articles > > Hi, QED's write performance optimization has been added to qcow2 > (-o lazy_refcounts=on). > > qcow2 has been optimized further in the meantime and is the > recommended image file format if raw lacks features that you need. Also, -snapshots uses "cache=unsafe", so there should be no performance difference between the two anyway. Random idea: should qcow2 always use lazy refcounts if it receives "cache=unsafe"? Paolo -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJVZFJqAAoJEL/70l94x66D2iwH/0GqHdLooig5uWRzUxVXx0ty kPx1dPWBnRbC2rid1n7BHlm/uCSoKZ8lURV2od3Jz97Mv/0/EIpT8nKvOb6/Sfpm 360hfZMKytTTytCLg2KvEPkXyBgvZZhIAHLb38H2kZxpis2lf+x3Ln2dRYvIfXNk A2caRZIH7AH99krQjSImZlM58Q3VQhs9QUsUe0zHrjCznq5pjYV8POSeiDb5l41S xrVkeVEBTwfSYaK2iBy9NTnlFUB5iXsIO5Ax8WEb5nRH18mSeH64En+yfe6kzOKh qSVA3K6aS6aWuSjYyenGITcntpWUGPOo4R7fmJJVVgLqZDAmBtI70am9IqLbcW8= =OUZz -----END PGP SIGNATURE-----