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October 20, 2016 20:07
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I was asked to investigate snapshots on lvm. I still prefer ZFS over LVM, but if you only have LVM you at least have lvmsync ( Thanks to Matt for his fine work on https://github.com/mpalmer/lvmsync )
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| #!/bin/bash | |
| # this must exit on any error | |
| set -e | |
| initiate_pull_snapshots(){ | |
| ssh ${DEST_HOST} lvcreate --size 10 --snapshot --name ${LOGICAL_VOL}-current ${VOL_NAME}/${LOGICAL_VOL} | |
| ssh ${DEST_HOST} dd if=/dev/${VOL_NAME}/${LOGICAL_VOL}-current bs=1M | dd of=/dev/${CLOUD_VOLUME}/${LOGICAL_VOL} bs=1M | |
| } | |
| # NB: The disk must have ${CHANGE_SIZE} space free to store all of the changes untill the next snapshot | |
| # *** If the changes are greater than ${CHANGE_SIZE}, the snapshot becomes corrupt, thus loosing all changes since. | |
| loop_in_cron_pull(){ | |
| ssh ${DEST_HOST} lvcreate --size ${CHANGE_SIZE} --snapshot --name ${LOGICAL_VOL}-new ${VOL_NAME}/${LOGICAL_VOL} | |
| ssh ${DEST_HOST} lvmsync --stdout /dev/${CLOUD_VOLUME}/${LOGICAL_VOL}-current | lvmsync --apply - /dev/${VOL_NAME}/${LOGICAL_VOL} | |
| # THE FOLLOWING MUST NOT RUN UNTILL ${VOL_NAME}/${LOGICAL_VOL}-current has succefully transfered! | |
| # | |
| ssh ${DEST_HOST} lvremove -f ${VOL_NAME}/${LOGICAL_VOL}-current | |
| ssh ${DEST_HOST} lvrename ${VOL_NAME}/${LOGICAL_VOL}-new ${VOL_NAME}/${LOGICAL_VOL}-current | |
| } |
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