From: Tomasz Chmielewski <mangoo@wpkg.org>
To: Dietmar Maurer <dietmar@proxmox.com>
Cc: Chris Webb <chris@arachsys.com>,
Javier Guerra <javier@guerrag.com>,
MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Avi Kivity <avi@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] Re: [ANNOUNCE] Sheepdog: Distributed Storage System for KVM
Date: Sun, 25 Oct 2009 11:55:32 +0100 [thread overview]
Message-ID: <4AE42EA4.5080009@wpkg.org> (raw)
In-Reply-To: <90D306BE6EBC8D428A824FBBA7A3113D012F07D53B@ronja.maurer-it.com>
Dietmar Maurer wrote:
>> Also, on _loaded_ systems, I noticed creating/removing logical volumes
>> can take really long (several minutes); where allocating a file of a
>> given size would just take a fraction of that.
>
> Allocating a file takes much longer, unless you use a 'sparse' file.
If you mean "allocating" like with:
dd if=/dev/zero of=image bs=1G count=50
Then of course, that's a lot of IO.
As you mentioned, you can create a sparse file (but then, you'll end up
with a lot of fragmentation).
But a better way would be to use persistent preallocation (fallocate),
instead of "traditional" dd or a sparse file.
--
Tomasz Chmielewski
http://wpkg.org
WARNING: multiple messages have this Message-ID (diff)
From: Tomasz Chmielewski <mangoo@wpkg.org>
To: Dietmar Maurer <dietmar@proxmox.com>
Cc: Chris Webb <chris@arachsys.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
Avi Kivity <avi@redhat.com>, Javier Guerra <javier@guerrag.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Subject: Re: [Qemu-devel] Re: [ANNOUNCE] Sheepdog: Distributed Storage System for KVM
Date: Sun, 25 Oct 2009 11:55:32 +0100 [thread overview]
Message-ID: <4AE42EA4.5080009@wpkg.org> (raw)
In-Reply-To: <90D306BE6EBC8D428A824FBBA7A3113D012F07D53B@ronja.maurer-it.com>
Dietmar Maurer wrote:
>> Also, on _loaded_ systems, I noticed creating/removing logical volumes
>> can take really long (several minutes); where allocating a file of a
>> given size would just take a fraction of that.
>
> Allocating a file takes much longer, unless you use a 'sparse' file.
If you mean "allocating" like with:
dd if=/dev/zero of=image bs=1G count=50
Then of course, that's a lot of IO.
As you mentioned, you can create a sparse file (but then, you'll end up
with a lot of fragmentation).
But a better way would be to use persistent preallocation (fallocate),
instead of "traditional" dd or a sparse file.
--
Tomasz Chmielewski
http://wpkg.org
next prev parent reply other threads:[~2009-10-25 10:55 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-21 5:13 [ANNOUNCE] Sheepdog: Distributed Storage System for KVM MORITA Kazutaka
2009-10-21 5:13 ` [Qemu-devel] " MORITA Kazutaka
2009-10-21 8:28 ` Nikolai K. Bochev
2009-10-21 8:28 ` [Qemu-devel] " Nikolai K. Bochev
2009-10-21 8:45 ` Nikolai K. Bochev
2009-10-21 8:45 ` [Qemu-devel] " Nikolai K. Bochev
2009-10-23 9:59 ` MORITA Kazutaka
2009-10-23 9:59 ` [Qemu-devel] " MORITA Kazutaka
2009-10-21 9:08 ` Dietmar Maurer
2009-10-21 9:08 ` [Qemu-devel] " Dietmar Maurer
2009-10-23 10:06 ` MORITA Kazutaka
2009-10-23 10:06 ` [Qemu-devel] " MORITA Kazutaka
2009-10-23 10:17 ` Chris Webb
2009-10-23 10:17 ` [Qemu-devel] " Chris Webb
2009-10-23 10:26 ` Chris Webb
2009-10-23 10:26 ` [Qemu-devel] " Chris Webb
2009-10-23 11:10 ` Dietmar Maurer
2009-10-23 11:10 ` [Qemu-devel] " Dietmar Maurer
2009-10-23 11:45 ` Dietmar Maurer
2009-10-23 11:45 ` [Qemu-devel] " Dietmar Maurer
2009-10-21 9:08 ` Dietmar Maurer
2009-10-22 15:30 ` Avi Kivity
2009-10-22 15:30 ` [Qemu-devel] " Avi Kivity
2009-10-22 16:28 ` Anthony Liguori
2009-10-22 16:28 ` [Qemu-devel] " Anthony Liguori
2009-10-22 22:09 ` Alexander Graf
2009-10-22 22:09 ` [Qemu-devel] " Alexander Graf
2009-10-23 10:41 ` MORITA Kazutaka
2009-10-23 10:41 ` [Qemu-devel] " MORITA Kazutaka
2009-10-23 11:10 ` Alexander Graf
2009-10-23 11:10 ` [Qemu-devel] " Alexander Graf
2009-10-23 16:17 ` MORITA Kazutaka
2009-10-23 14:14 ` Javier Guerra
2009-10-23 14:14 ` [Qemu-devel] " Javier Guerra
2009-10-23 14:58 ` Chris Webb
2009-10-23 14:58 ` Chris Webb
2009-10-23 15:10 ` Javier Guerra
2009-10-23 15:10 ` Javier Guerra
2009-10-23 17:05 ` Tomasz Chmielewski
2009-10-23 17:05 ` Tomasz Chmielewski
2009-10-25 8:44 ` Dietmar Maurer
2009-10-25 8:44 ` Dietmar Maurer
2009-10-25 10:55 ` Tomasz Chmielewski [this message]
2009-10-25 10:55 ` Tomasz Chmielewski
2009-10-23 15:40 ` FUJITA Tomonori
2009-10-23 15:40 ` [Qemu-devel] " FUJITA Tomonori
2009-10-25 5:36 ` Avi Kivity
2009-10-25 5:36 ` [Qemu-devel] " Avi Kivity
2009-10-25 8:51 ` Dietmar Maurer
2009-10-25 8:51 ` [Qemu-devel] " Dietmar Maurer
2009-10-26 6:53 ` MORITA Kazutaka
2009-10-26 6:53 ` [Qemu-devel] " MORITA Kazutaka
2009-10-22 18:46 ` Avishay Traeger
2009-10-22 18:46 ` [Qemu-devel] " Avishay Traeger
2009-10-22 18:53 ` Avishay Traeger
2009-10-23 15:41 ` MORITA Kazutaka
2009-10-23 11:22 ` Dietmar Maurer
2009-10-23 11:22 ` [Qemu-devel] " Dietmar Maurer
2009-10-23 19:39 ` [Qemu-devel] " MORITA Kazutaka
2009-10-23 19:45 ` Javier Guerra
2009-10-23 19:45 ` Javier Guerra
2009-10-24 2:49 ` MORITA Kazutaka
2009-10-24 2:49 ` MORITA Kazutaka
2009-10-28 3:53 ` MORITA Kazutaka
2009-10-28 3:53 ` [Qemu-devel] " MORITA Kazutaka
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