From: Roman Mamedov <rm@romanrm.net>
To: Adam Borowski <kilobyte@angband.pl>
Cc: Christoph Anton Mitterer <calestyo@scientia.net>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: zerofree btrfs support?
Date: Sat, 10 Mar 2018 23:31:27 +0500 [thread overview]
Message-ID: <20180310233127.0dfa7823@natsu> (raw)
In-Reply-To: <20180310155022.wtdmwiyxu7mxt74s@angband.pl>
On Sat, 10 Mar 2018 16:50:22 +0100
Adam Borowski <kilobyte@angband.pl> wrote:
> Since we're on a btrfs mailing list, if you use qemu, you really want
> sparse format:raw instead of qcow2 or preallocated raw. This also works
> great with TRIM.
Agreed, that's why I use RAW. QCOW2 would add a second layer of COW on top of
Btrfs, which sounds like a nightmare. Even if you would run those files as
NOCOW in Btrfs, somehow I feel FS-native COW is more efficient than emulating
it in userspace with special format files.
> > It works, just not with some of the QEMU virtualized disk device drivers.
> > You don't need to use qemu-img to manually dig holes either, it's all
> > automatic.
>
> It works only with scsi and virtio-scsi drivers. Most qemu setups use
> either ide (ouch!) or virtio-blk.
It works with IDE as well.
--
With respect,
Roman
next prev parent reply other threads:[~2018-03-10 18:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-10 2:55 zerofree btrfs support? Christoph Anton Mitterer
2018-03-10 8:16 ` Adam Borowski
2018-03-10 14:19 ` Christoph Anton Mitterer
2018-03-10 14:37 ` Roman Mamedov
2018-03-10 15:50 ` Adam Borowski
2018-03-10 16:58 ` Christoph Anton Mitterer
2018-03-10 18:31 ` Roman Mamedov [this message]
2018-03-10 18:39 ` Christoph Anton Mitterer
2018-03-10 16:55 ` Christoph Anton Mitterer
2018-03-14 19:38 ` David Sterba
2018-03-15 2:54 ` Christoph Anton Mitterer
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