previously i asked about how to access a partition in LV. this is a nice solution from IET user. Ming -------- Forwarded Message -------- > From: Dr. Net! - Eugen Rieck <eugen@drnet.at> > To: iscsitarget-devel@lists.sourceforge.net > Subject: Re: [Iscsitarget-devel] RE:local mounting of a drive formated > byan initiator > Date: Tue, 23 Aug 2005 21:36:41 +0200 > Hi all - solution found. > > > >so u export /dev/sda3 to ini side as a DISK, which is not a partition > > >any more. then partition it, use it, and disconnect from it. > > > > > >but at local side, u can not access a partition in a partition. :P > > Exporting the whole disk sda is not the perfect solution - when you export a > raid (mdX) you have the same problem, BUT: > > No need for kpartx. There is an easy solution to this - use a loop device! > > A Partition is nothing else than a continuous part of the underlying block > device - so you can touch it with a loop device with offset and size limit. > > I assume you exported /dev/sda3 via IET > > So you: > 1.) Get the partition geometry - You only need to do this once > > fdisk -lu /dev/sda3 > You see something like > > Disk /dev/sda3: 180.0 GB, 180034928640 bytes > 255 heads, 63 sectors/track, 21888 cylinders > Units = cylinders of 16065 * 512 = 8225280 bytes > > Device Boot Start End Blocks Id System > /dev/sda3p1 63 351614654 175807296 7 HPFS/NTFS > > Note the Start (63) and End (351614654 ) Values - they tell you, that inside > sda3 your "partition in a partition" starts at sector 63 and ends at sector > 351614654 > So: > Offset=63 Blocks=63*512=32256 > Length=351614654 -63+1=351614592 Blocks=180026671104 Bytes > > If you use the last partition up to the end of the disk, you don't need the > length, but I'll take it here for clarity > > 2.) Get a free loop device - you have to do this for every boot (I'll fix up > a script to automate it and follow up later) > > Variante 1 (New versions of losetup): > losetup -a > You see something like > /dev/loop0: [0805]:1740 (/var/install/suse93.dvd) > /dev/loop7: [0805]:2065 (/var/tmp/aoe/volume) > > You now know, that loop devices 0 and 7 are in use, making 1-6 free. > No output means all loop devices are free > > Variante 2 (if 1 fails on older versions): > If losetup -a complains, you have an older version that dosesn't understand > the -a flag. in this case do > losetup /dev/loop0 > losetup /dev/loop1 > ... > until you get "no such device or address" - again you have found a free loop > device. > > I now assume that loop1 is free > > 3.) set up the loop device > > losetup -o 32256 -s 180026671104 /dev/loop1 /dev/sdc3 > > -o 32256 is offset from 1.) > -s 180026671104 is length from 1.) > /dev/loop1 is free loop device from 2.) > /dev/sdc3 is your exported volume > > 4.) mount the loop device > > mount /dev/loop1 /your/mount/point > > Done! > > I just tried this with my box - this is where the numbers come from > > Have fun! > > Regards, Eugen > > :-) Eugen Rieck (-: > eugen@drnet.at > > Programmer: Biological device, > designed to convert coffee into code > > > > ------------------------------------------------------- > SF.Net email is Sponsored by the Better Software Conference & EXPO > September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices > Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA > Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf > _______________________________________________ > Iscsitarget-devel mailing list > Iscsitarget-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/iscsitarget-devel _______________________________________________ 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/
