I tryed the same procedure on my rh9 box; dident work for me either. I then used dd to create a random file the same size as the lv i had created, copyed the data onto the lv, copyed the data off the lv, and did a 'cmp'...they differ at byte1, line1. On Wed, 2003-09-24 at 04:33, Heinz J . Mauelshagen wrote: > Never seen this here. > Did a quick test and it works with 1.0.7 on 2.4.21 vanilla here. > It could be a problem with that RedHat kernel. > > Regards, > Heinz -- The LVM Guy -- > > > On Tue, Sep 23, 2003 at 05:14:31PM -0400, Montgomery, Kendal L wrote: > > I've seen a few things about using lvm on a loopback filesystem, but nothing > > concrete, so I tried it myself. Most everything works okay until I get to > > acutally mounting the filesystem. Here are the steps I did: > > > > [root@klmontg tmp]# dd if=/dev/zero of=fake_disk.img bs=1M count=500 > > 500+0 records in > > 500+0 records out > > [root@klmontg tmp]# losetup /dev/loop0 fake_disk.img > > [root@klmontg tmp]# pvcreate /dev/loop0 > > pvcreate -- physical volume "/dev/loop0" successfully created > > > > [root@klmontg tmp]# vgcreate /dev/vgtest /dev/loop0 > > vgcreate -- INFO: using default physical extent size 4 MB > > vgcreate -- INFO: maximum logical volume size is 255.99 Gigabyte > > vgcreate -- doing automatic backup of volume group "vgtest" > > vgcreate -- volume group "vgtest" successfully created and activated > > > > [root@klmontg tmp]# lvcreate --name lv_one --size 200M /dev/vgtest > > lvcreate -- doing automatic backup of "vgtest" > > lvcreate -- logical volume "/dev/vgtest/lv_one" successfully created > > > > [root@klmontg tmp]# mke2fs /dev/vgtest/lv_one > > mke2fs 1.32 (09-Nov-2002) > > Filesystem label= > > OS type: Linux > > Block size=1024 (log=0) > > Fragment size=1024 (log=0) > > 51200 inodes, 204800 blocks > > 10240 blocks (5.00%) reserved for the super user > > First data block=1 > > 25 block groups > > 8192 blocks per group, 8192 fragments per group > > 2048 inodes per group > > Superblock backups stored on blocks: > > 8193, 24577, 40961, 57345, 73729 > > > > Writing inode tables: done > > Writing superblocks and filesystem accounting information: done > > > > This filesystem will be automatically checked every 26 mounts or > > 180 days, whichever comes first. Use tune2fs -c or -i to override. > > [root@klmontg tmp]# e2fsck /dev/vgtest/lv_one > > e2fsck 1.32 (09-Nov-2002) > > Couldn't find ext2 superblock, trying backup blocks... > > e2fsck: Bad magic number in super-block while trying to open > > /dev/vgtest/lv_one > > > > The superblock could not be read or does not describe a correct ext2 > > filesystem. If the device is valid and it really contains an ext2 > > filesystem (and not swap or ufs or something else), then the superblock > > is corrupt, and you might try running e2fsck with an alternate superblock: > > e2fsck -b 8193 <device> > > > > [root@klmontg tmp]# e2fsck -b 8193 /dev/vgtest/lv_one > > e2fsck 1.32 (09-Nov-2002) > > e2fsck: Bad magic number in super-block while trying to open > > /dev/vgtest/lv_one > > > > The superblock could not be read or does not describe a correct ext2 > > filesystem. If the device is valid and it really contains an ext2 > > filesystem (and not swap or ufs or something else), then the superblock > > is corrupt, and you might try running e2fsck with an alternate superblock: > > e2fsck -b 8193 <device> > > > > [root@klmontg tmp]# mount /dev/vgtest/lv_one /mnt > > mount: you must specify the filesystem type > > [root@klmontg tmp]# mount -t ext2 /dev/vgtest/lv_one /mnt > > mount: wrong fs type, bad option, bad superblock on /dev/vgtest/lv_one, > > or too many mounted file systems > > > > As you can see, one the filesystem was made, nothing else works. I can't > > fsck the filesystem on the new logical volume, or mount it. This is > > obviously a problem since, well, it's useless unless I can mount it. > > > > I'm using RedHat 9 with the 2.4.20-20.9 kernel. I've also tried this on > > RedHat 8 on another box. I got the latest version of util-linux which is > > 2.11z and compiled that (in case it was a possible bug in mount 2.11y which > > comes with redhat). I'm using lvm 1.0.3-12 that comes with redhat 9. I > > have not tried getting the latest lvm tools. That's my next step... > > > > Anyone else had this problem, or tried doing this? The reason I wanted to > > do this in the first place is so I can test snapshots. I want to be able to > > have a filesystem which is static, that I will then take a snapshot of, then > > change things on it, and then use the snapshot to bring it back to it's > > original form. I know there is some work on union filesystems or > > translucent filesystems, and such things, but none of it seems mature > > enough, so this solution seemed like it might work until I hit this snag. > > > > Is anyone else doing this (lvm on loopback)? Does anyone have it working > > correctly? Am I doing something wrong? Do I need a different version of > > something? > > > > Thanks in advance for any help. > > > > Kendal. > > > > _______________________________________________ > > linux-lvm mailing list > > linux-lvm@sistina.com > > http://lists.sistina.com/mailman/listinfo/linux-lvm > > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > *** Software bugs are stupid. > Nevertheless it needs not so stupid people to solve them *** > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > > Heinz Mauelshagen Sistina Software Inc. > Senior Consultant/Developer Am Sonnenhang 11 > 56242 Marienrachdorf > Germany > Mauelshagen@Sistina.com +49 2626 141200 > FAX 924446 > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
