From: Rich Freeman <r-btrfs@thefreemanclan.net>
To: Lionel Bouton <lionel-subscription@bouton.name>
Cc: Duncan <1i5t5.duncan@cox.net>, Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: BTRFS as image store for KVM?
Date: Sun, 4 Oct 2015 08:21:53 -0400 [thread overview]
Message-ID: <CAGfcS_=9uf359-uBHfEXhUC3HTpkjzE7vMwG1iOR2Ld0u3nFTg@mail.gmail.com> (raw)
In-Reply-To: <56111598.2080403@bouton.name>
On Sun, Oct 4, 2015 at 8:03 AM, Lionel Bouton
<lionel-subscription@bouton.name> wrote:
>
> This focus on single reader RAID1 performance surprises me.
>
> 1/ AFAIK the kernel md RAID1 code behaves the same (last time I checked
> you need 2 processes to read from 2 devices at once) and I've never seen
> anyone arguing that the current md code is unstable.
Perhaps, but with btrfs it wouldn't be hard to get 1000 processes
reading from a raid1 in btrfs and have every single request directed
to the same disk with the other disk remaining completely idle. I
believe the algorithm is just whether the pid is even or odd, and
doesn't take into account disk activity at all, let alone disk
performance or anything more sophisticated than that.
I'm sure md does a better job than that.
--
Rich
next prev parent reply other threads:[~2015-10-04 12:21 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-15 21:34 BTRFS as image store for KVM? Gert Menke
2015-09-16 3:00 ` Chris Murphy
2015-09-16 3:57 ` Duncan
2015-09-16 11:35 ` Brendan Heading
2015-09-16 12:25 ` Austin S Hemmelgarn
2015-09-16 12:41 ` Paul Jones
2015-09-17 17:56 ` Gert Menke
2015-09-17 18:35 ` Chris Murphy
2015-09-17 21:32 ` Gert Menke
2015-09-18 2:00 ` Duncan
2015-09-18 8:32 ` Gert Menke
2015-09-23 7:28 ` Russell Coker
2015-09-18 14:13 ` Austin S Hemmelgarn
2015-09-23 7:24 ` Russell Coker
2015-09-17 18:46 ` Mike Fleetwood
2015-09-17 19:43 ` Hugo Mills
2015-09-17 21:49 ` Gert Menke
2015-09-18 2:22 ` Duncan
2015-09-18 8:59 ` Gert Menke
2015-09-17 22:41 ` Sean Greenslade
2015-09-18 7:34 ` Gert Menke
2015-09-17 4:19 ` Paul Harvey
2015-09-20 1:26 ` Jim Salter
2015-09-25 12:48 ` Rich Freeman
2015-09-25 12:56 ` Jim Salter
2015-09-25 13:04 ` Austin S Hemmelgarn
[not found] ` <5605483A.7040103@jrs-s.net>
2015-09-25 13:46 ` Austin S Hemmelgarn
2015-09-25 13:52 ` Jim Salter
2015-09-25 14:02 ` Timofey Titovets
2015-09-25 14:20 ` Austin S Hemmelgarn
2015-09-29 14:12 ` Gert Menke
2015-10-02 4:21 ` Russell Coker
2015-10-02 12:07 ` Austin S Hemmelgarn
2015-10-03 8:32 ` Russell Coker
2015-10-04 2:09 ` Duncan
2015-10-04 12:03 ` Lionel Bouton
2015-10-04 12:21 ` Rich Freeman [this message]
2015-10-05 8:19 ` Duncan
2015-10-05 8:43 ` Erkki Seppala
2015-10-05 8:51 ` Roman Mamedov
2015-10-05 11:16 ` Lionel Bouton
2015-10-05 11:40 ` Rich Freeman
2015-10-05 11:54 ` Austin S Hemmelgarn
[not found] ` <RPG31r00t34oj7R01PG5Us>
2015-10-05 14:04 ` Duncan
2015-10-05 15:59 ` Austin S Hemmelgarn
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