I''m trying to create a multi-device filesystem on top of regular files (not actual disks), and mount that to a loopback device. For a filesystem created on a single file, it works fine, but for a filesystem across multiple files, it doesn''t. dd if=/dev/zero of=img1 bs=4096 count=65536 dd if=/dev/zero of=img2 bs=4096 count=65536 dd if=/dev/zero of=img3 bs=4096 count=65536 dd if=/dev/zero of=img4 bs=4096 count=65536 mkfs.btrfs img1 mount -o loop -t btrfs img1 /mnt/test # works mkfs.btrfs img1 img2 img3 img4 mount -o loop -t btrfs img1 /mnt/test # fails When I try to mount with multiple files, it also prints a message to syslog: Jun 15 00:32:10 3vil device fsid a147d6b950f66dca-3e2e7f52011c93b0 devid 4 transid 9 /dev/loop/0 Jun 15 00:32:10 3vil btrfs: failed to read chunk tree on loop0 Jun 15 00:32:10 3vil btrfs: open_ctree failed Am I doing something wrong, or is this use case broken right now? --Ravi -- 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
2009/6/15 Ravi Pinjala <ravi@p-static.net>:> I''m trying to create a multi-device filesystem on top of regular files > (not actual disks), and mount that to a loopback device. For a > filesystem created on a single file, it works fine, but for a filesystem > across multiple files, it doesn''t. > > > > dd if=/dev/zero of=img1 bs=4096 count=65536 > dd if=/dev/zero of=img2 bs=4096 count=65536 > dd if=/dev/zero of=img3 bs=4096 count=65536 > dd if=/dev/zero of=img4 bs=4096 count=65536 > > mkfs.btrfs img1 > mount -o loop -t btrfs img1 /mnt/test # works > > mkfs.btrfs img1 img2 img3 img4 > mount -o loop -t btrfs img1 /mnt/test # fails > >Please setup loop devices for the image files manually. In this case, ''mount -o loop'' can''t do it for you. For example: mkfs.btrfs img1 img2 img3 img4 for i in `seq 1 4`; do losetup /dev/loop$ img$i; done btrfsctl -a mount -t btrfs /dev/loop1 /mnt/test See below for more information: http://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices Yan, Zheng -- 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