I didn't see any replies to this, so I thought I'd post what I've found. You have to specify a smaller extent size when creating the volume group. The default extent size is 4MB, which is larger than your physical device on /dev/loop1 (use the -s option) For example, try this instead, which would give 4 extents on the 1MB physical device on /dev/loop1 (I think. I am not certain about how much metadata exists on the physical device for LVM2) >vgcreate SmallDiskGroup -s256k /dev/loop0 # create a new volumegroup using the >loop0 device as phisical volume. Steve. On Mon, 29 Sep 2008 11:44:40 +0200, you wrote: >Hello Bryn, >I haven't had the time yet to try Stuart's suggestion... I've re did my >attempt to create the lv though, and this time with the -vvv option in >the step where I create the lv. >my steps: >dd if=/dev/sdb1 of=./disk0 # copy a existing LVM-partition to a file >losetup -f ./disk0 # link the file to a loop device >pvcreate /dev/loop0 # create a pv using the file >vgcreate SmallDiskGroup /dev/loop0 # create a new volumegroup using the >loop0 device as phisical volume. >vgchange -a y SmallDiskGroup #Activate the volumegroup > >nb. vgdisplay SmallDiskGroup gives 'Act PV 1' but 'MAX LV 0' > >the output of lvcreate -vvv -L1 -nSmallDiskVolume SmallDiskGroup is >downloadable here: http://pastebin.com/pastebin.php?dl=m2b9dcd7f > >I hope you can find anything. > >Greetings, >Geert > >On Mon, 2008-09-29 at 10:08 +0100, Bryn M. Reeves wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> geert Geurts wrote: >> > So what I did first create a LVM partition of 1MB on a memorystick and then >> > change the if of dd to point to the LVM partition, I'm now able to pvcreate >> > /dev/loop0, vgcreate SmallDisk /dev/loop0. >> > But I'm unable to create a logical volume in the SmallDisk group... >> > what am I doing wrong here? is it even possible if not why? >> >> Hi Geert, >> >> What was the error you were getting at this point? If possible, can you >> use a service like pastebin.com to post the complete output of "lvcreate >> - -vvv" with the options you're using for the SmallDisk VG. That should >> give enough detail to have some idea where it's failing. >> >> I think the idea is reasonable enough although you'll probably need to >> do some fiddling around to get the size/number of the gmailfs volumes >> right to give good performance. >> >> Snapshots could definitely work here but I think it might be a bit >> tricky without some of the patches that are currently outstanding for >> device-mapper, esp. Mikulas' snapshot merging patches which you'd need >> to "restore" one of the COW areas. See the thread here: >> >> http://kerneltrap.org/Linux/LVM_Snapshot_Merging >> >> Regards, >> Bryn. >> >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1.4.9 (GNU/Linux) >> Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org >> >> iEYEARECAAYFAkjgmxgACgkQ6YSQoMYUY96LegCcCHPZNLfhTUjIrsLiJcgROTDV >> +SwAoLFQDiGpkZl5tpEFW5hjFH+6OuAj >> =i+W8 >> -----END PGP SIGNATURE----- >> >> _______________________________________________ >> linux-lvm mailing list >> linux-lvm@redhat.com >> https://www.redhat.com/mailman/listinfo/linux-lvm >> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > >_______________________________________________ >linux-lvm mailing list >linux-lvm@redhat.com >https://www.redhat.com/mailman/listinfo/linux-lvm >read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
