On Mon, Feb 17, 2014 at 4:00 AM, Zdenek Kabelac <zkabelac@redhat.com> wrote: > Dne 14.2.2014 20:21, Jeremy Smith napsal(a): >> >> I have a system currently using LVM2 that was originally set up on >> RHEL5 (where thin provisioning was not supported). >> This system would greatly benefit from the newer thin provisioning >> features, and so I am investigating upgrading to RHEL6 so that I may >> take advantage. My question is this: Can I convert existing LVM2 >> "thick" logical volumes into thinly-provisioned volumes on the fly? >> >> This page: >> >> https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Logical_Volume_Manager_Administration/thinly_provisioned_volume_creation.html >> >> lead me to believe that it is possible: >> "You can use the --thinpool parameter of the lvconvert command to >> convert an existing logical volume to a thin volume." >> >> with the following: >> >> lvconvert --thinpool vg001/lv1 --poolmetadata vg001/lv2 > > > > Sounds like misunderstanding which needs fix/enhancement of this doc page - > we will need to enhance lvconvert command to write big warning about this > operation. > > This conversion is converting volume to 'data' volume - but it's not about > preserving content of LV1 as LV1 - it will serve as en empty pool. > > The primary purpose is - you can build 'any' type of LV for data volume > and 'any' type of LV for metadata volume (i.e. special layout for > raid/mirror) > and then you 'create' for these 2 volumes your thin pool - since normally > you can't create mirrored data & metadata volumes and thin pool in 1 > command, > and you can't easily select where the metadata should be placed > (i.e. data on spindle, metadata on SSD). > >> >> Am I doing something wrong here? >> Or am I going to have to create a new thin pool, new thin logical >> volumes, and copy the data over? > > > There is not yet support for direct conversion of LV to thin-LV. > The only currently supported method is to use your thick-LV as an external > origin LV for your thin-LV volume. > > i.e. you create your thin-pool LV + and then thin-LV volume with external > origin that will use original thick-LV (external origin need to be > read-only volume) > > Here are the conversion steps: > > lvcreate -Lsize_of_data_pool -T vg/pool > lvconvert -T vg/thick_LV --originname new_thick_LV_name --thinpool vg/pool > > Disadvantage here is you cannot merge changes from thin volume back to > original thick volume. You can however remove thin-LV and use again your > thick-LV as normal volume - i.e. thin-LV is basically snapshot. > > Now hint for recovery - if you have not yet written anything to thin-LV from > newly create thin-pool. You could restore back to your previous > configuration > via vgcfgrestore --force. > > Zdenek > Zdenek, Thank you. I was able to perform migration of some of my LVs, but now I have ran into a problem: the thin pool metadata has ran out of space :-( I am running LVM 2.02.98(2) (2012-10-15) on kernel 3.11.0-18-generic (Ubuntu server 13.10), which -- as I understand from your talk at https://www.youtube.com/watch?v=dGax09aw7WI -- does not support live resizing of the pool metadata. You mention in that talk that there is a manual offline pool metadata resize method that can be done on kernels prior to 3.14. I was not able to find details anywhere on how to accomplish this. Could you point me in the right direction on how to fix a thin pool (and its thin logical volumes) that has reached the metadata size limit? It would be greatly appreciated. Regards, -- Jeremy Smith Systems Administrator eSilo, LLC. 1530 Cypress Drive, Suite H Jupiter, FL. 33469 561-747-6880 x 412 (Phone) 800-747-9255 x 412 (Toll Free) 866-598-1358 (After Hours) 561-747-6488 (Fax) jeremy@esilo.com _______________________________________________ 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/
