From: Goffredo Baroncelli <kreijack@gmail.com>
To: Matt Brown <shadowfax@gmx.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Mounting raid without a btrfsctl scan
Date: Sat, 15 May 2010 16:36:08 +0200 [thread overview]
Message-ID: <201005151636.08437.kreijack@libero.it> (raw)
In-Reply-To: <4BEE817A.7060604@gmx.com>
On Saturday 15 May 2010, Matt Brown wrote:
> Hi,
Hi Matt,
>
> Would it be possible and feasible to support mounting btrfs
> raid/multi-device filesystems without having to run 'btrfsctl -a'?
>
> Currently, as you may know, if a one wants to attach a btrfs raid
> filesystem to a system (usb, hotswap, reboot, etc), the user or program
> has to run:
>
> btrfsctl -a (or similar)
> mount /dev/sdb1 /mount/point
>
> While this works, it will require patching of various subsystems
> involved with managing disks, such as udev, mkinitrd, dracut, hal, and
> others. Each one will have to know to scan, then mount.
In a my previous post ([RFC] btrfs, udev and btrfs - 16/April 2010), I
suggested a solution for this kind of problem. I a Debian/Ubuntu system it is
not necessary to patch anything, it is only required to put some files in the
initramfs-tool configure directories.
IIRC, also the md (RAID) subsystem require a scan from the user space to find
and activate the volumes. I think also dm (LVM) subsystem requires the same.
>
> For example, I have a system that has a btrfs raid1 as root. However, I
> had to patch the boot loader (dracut) so during boot it would scan just
> before mounting the root filesystem.
>
> I filed a bug with dracut, but the more I think of it, the more it seems
> that either mount.btrfs should be taking care of this, or another part
> of btrfs.
If it would be mount.btrfs to perform the scan, that means a scan for every
mounting. I think that is better to separate the two function. The scan has to
be performed a device discovery time, and not a the mounting time.
>
> Any thoughts or plans on the matter?
>
> Thanks,
> Matt
BR
Goffredo
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) <kreijackATinwind.it>
Key fingerprint = 4769 7E51 5293 D36C 814E C054 BF04 F161 3DC5 0512
next prev parent reply other threads:[~2010-05-15 14:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-15 11:11 Mounting raid without a btrfsctl scan Matt Brown
2010-05-15 14:36 ` Goffredo Baroncelli [this message]
2010-05-15 16:47 ` Sebastian 'gonX' Jensen
2010-05-16 0:02 ` Tomasz Torcz
2010-05-16 0:41 ` Sebastian 'gonX' Jensen
2010-05-16 18:44 ` Goffredo Baroncelli
2010-05-16 19:38 ` Sebastian 'gonX' Jensen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201005151636.08437.kreijack@libero.it \
--to=kreijack@gmail.com \
--cc=kreijack@libero.it \
--cc=linux-btrfs@vger.kernel.org \
--cc=shadowfax@gmx.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).