From mboxrd@z Thu Jan 1 00:00:00 1970 From: TARUISI Hiroaki Subject: Re: Unable to mount loopback devices in RAID mode Date: Wed, 02 Dec 2009 08:52:40 +0900 Message-ID: <4B15AC48.6040506@jp.fujitsu.com> References: <200911192026.04694.lists-receive@programmierforen.de> <20091130042851.GG25509@jsoft.dyndns.org> <4B13C408.10606@hp.com> <200911302025.22773.lists-receive@programmierforen.de> <4B14B022.4080102@jp.fujitsu.com> <23a15590912010227v38b62a51r63e5d83fdd9fec4c@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: lists-receive@programmierforen.de, jowens@hp.com, linux-btrfs@vger.kernel.org To: skolima@gmail.com Return-path: In-Reply-To: <23a15590912010227v38b62a51r63e5d83fdd9fec4c@mail.gmail.com> List-ID: Yes. 'device' options work good on boot. (There may be trivial differences, perhaps.) Both 'btrfsctl -a|A' and device option of mount calls a same device collection function, 'scan_one_device' and by this function btrfs knows devices for btrfs. # But, there's no mount option like 'btrfsctl -a', so # option string grows longer and longer as number of # devices increases... Leszek Ciesielski wrote: > On Tue, Dec 1, 2009 at 6:56 AM, TARUISI Hiroaki > wrote: >> Btrfs collects block device information when mount or mkfs >> (device_list_add in volumes.c), and know devid-device relation >> by collected information. So, if we make filesystem on plain >> file, btrfs cannot know devid-device relation. As a result, >> btrfs cannot know which is 'devid=n', and mount fails. Same as >> this, if collected relation is cleared by shutdown, mount fails. >> >> If wlee need to mount a filesystem without fail(cf, /etc/fstab line), >> we should specify 'device' options for every devices(except mount >> target device) like this. >> >> # mount -t btrfs -o device=/dev/loop2,device=/dev/loop3, >> device=/dev/loop4 /dev/loop1 /mnt/ >> (when a filesystem is constructed by /dev/loop[1-4]) >> >> Regards, >> taruisi > > Would this option ["mount -t btrfs -o device=/dev/sdb2 /dev/sda2 > /mnt"] work on boot, bypasing the need for "btrfsctl -a" to mount a > multi-device filesystem? > -- > 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 -- taruisi