On 09/02/2010 02:50 AM, Linda A. Walsh wrote: > I'm running low on space in my /backups partition. I looked at the > partitions and volumes to see what might be done (besides deleting old > backups), and noticed: > > pvs: > PV VG Fmt Attr PSize PFree > /dev/sdb1 Backups lvm2 a- 10.91T 3.15G You're running "pvs" which means you are looking at physical volumes. The "lvs" command would probably have been more useful. > --- > So I thought 'cool', I didn't make it the full size, and > I have some left...ok...(I didn't remember what I'd done, its > been a while). > > Run lvresize: > lvresize /dev/Backups/Backups -L +3.15G > Rounding up size to full physical extent 3.15 GB > Extending logical volume Backups to 10.91 TB > Logical volume Backups successfully resized You added 3.15G to your *logical* volume. This made it the same size (within rounding errors and ignoring the metadata, alignment & label overheads) as the physical volume you were looking at above. > Um...HELLO? Extending to 10.91? But it was at 10.91! You're mixing up your logical volumes (usable block devices allocated from an LVM2 volume group) with your physical volumes (underlying disks that provide the usable storage extents for the volume group). http://www.errorists.org/stuff/lvm/lvm-concepts.png The logical volume was 3.15G smaller before this operation - you can check this if you're using the default archiving settings in /etc/lvm/lvm.conf by looking for the "Backups" VG's archived metadata in /etc/lvm/archive. Look for the highest numbered version (this will be a backup of the current state _after_ the lvextend above) and then go back and look at the previous version. You can also review what operations have been done to the VG in the retained archives by running: # grep '^description' /etc/lvm/archive/<VG name>* E.g.: http://pastebin.com/M918gGGU > pvs: > PV VG Fmt Attr PSize PFree > /dev/sdb1 Backups lvm2 a- 10.91T 0 > > Well that was unimpressive. Only becaus eyou are still looking at _physical_ volumes. You might be more impressed if you ran the lvs command (or lvdisplay which has a multi-line record style of output by default) before and after. You'll only see changes in the output of the PFree attribute of pvs when you're just manipulating LVs; if you changed the disk size and used pvresize or ran vgextend to add a new disk you would see changes here but since you're just allocating more storage to the LVs in the volume group the only field to change is the amount of free space on the PV. # lvdisplay bmr_vg0/root --- Logical volume --- LV Name /dev/bmr_vg0/root VG Name bmr_vg0 LV UUID bn0t3S-GHAq-b3vK-bvUQ-gYey-acwt-efyd5Z LV Write Access read/write LV Status available # open 1 LV Size 17.81 GB Current LE 4560 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 lvs LV VG Attr LSize Origin Snap% Move Log Copy% Convert data bmr_vg0 -wi-ao 28.00G home bmr_vg0 -wi-ao 84.41G root bmr_vg0 -wi-ao 17.81G var bmr_vg0 -wi-ao 3.91G swap bmr_vg1 -wi-ao 3.91G > Number Start End Size File system Name Flags > 1 17.4kB 12.0TB 12.0TB backup lvm As Stuart pointed out this is just binary prefix vs. SI notations: http://physics.nist.gov/cuu/Units/binary.html http://en.wikipedia.org/wiki/Binary_Prefix http://en.wikipedia.org/wiki/International_System_of_Units Your space hasn't gone anywhere :) > How do I get my 1.09T back from lvm? That seems like awfully > high for an overhead number for lvm. I'd expect more like "0.09T". There's very little overhead to lvm in terms of space. Read through the metadata files in your archive directory and you'll see how the data is laid out. A few sectors are taken up with the LVM2 physical volume label, a few more (configurable) are occupied by the metadata buffer and on recent versions there may be some padding to provide optimal data alignment but the rest (from pe_start in the metadata) are all available for data allocation. Don't forget to resize the file system: # fsadm resize /dev/Backup/<LV Name> Regards, Bryn. _______________________________________________ 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/
