![]() Lvm is not included in the initramfs on the problematic systemĭracut should recognize the lvm signature on the disk and lvm should be included in the initramfs. The patch level and patching method is the same on both.Ī] On the problematic system, /dev/sda2 (PV for rootvg) has a dos partition table signatureĠx1fe dos Now on the problematic server, we wiped off the dos signature and upgraded the kernel and this time there was no issue The customer has 2 identical systems that were patched. Upgrade the OS via Satellite server using "yum update" command Version-Release number of selected component (if applicable): And while rebuilding the initramfs of the existing kernels, dracut does not include lvm in any of them thereby causing the system to not boot using any of the older kernels. Also, during the process of kernel upgrade, dracut creates initramfs of the latest kernel that is being installed AS WELL AS it rebuilds the initramfs of kernels that are already present on the system. So the issue is introduced at kernel upgrade. We do NOT need to explicitly use "-add lvm" while rebuilding initramfs Due to this all the logical volumes, volume groups and physical volumes mapped to that LVM metadata was not visible on the Linux server. Simply running "dracut -f " is sufficient. How to restore LVM metadata in Linux Earlier we had a situation wherein the LVM metadata from one of our CentOS 8 node was missing. To solve this issue, we simply need to enter rescue mode and rebuild initramfs. Straightforward.After upgrading from Rhel 7.6 to Rhel 7.7, dracut does not include lvm in the initramfs, thereby causing the system to not boot. Summing up, to have a mirror with LVM is cheap and pretty Instead of using a command such as cp -R I prefer using tar, because is cleaner and will copy absolutely all the files, here is the command:įirst move your old home hlab:# mv /home /home_tmp The last point is to copy the home data and add a line to /etc/fstab. The interesting part here, is the meaning of the attributes, you can make it out by means of “man”: LV VG Attr LSize Origin Snap% Move Log Copy% Convert Devices ![]() This correlates with the previous experiment and the hypothesis. It was also 164 faster in post-snapshot reads and 17 faster in post-snapshot writes. Btrfs was 107 faster in initial read scores and 24 faster in initial write scores. So instead of creating another partition, I omitted it.Īt this point is possible to show the mirror: hlab:# lvs -a -o +devices In this test, Btrfs outperformed LVM in every benchmark. Here is the command hlab:# lvcreate -m1 (-nosync) -L 110G -mirror-log core -n home volsīut default you need a third partition for keeping the logs, If you are familiarized with ZFS, at this point we have like zfs pool. Now you can create some volumes, which will appear in /dev/volname just take a look to the command: hlab:# vgcreate -A y vols /dev/sda5 /dev/sdb5 The above step is just a conventionality ( I see it like that) for telling that you have available some partitions or disks. ![]() PV UUID 0DfPHc-tXBn-dcYR-yKag-EL7j-RI4A-K9Eo0j The first thing is to add physical volumes, and by physical I mean, either partitions or whole disks, here is the way: hlab:# pvcreate /dev/sda5 /dev/sdb6 Warning: extended partition does not start at a cylinder boundary.ĭOS and Linux will interpret the contents differently. This will make the second disk’s partition table /dev/sdb identical to the the first hard drive /dev/sdb. Hlab:# sfdisk -d /dev/sda | sfdisk /dev/sdb If you work with Debian or a system based on: hlab:# aptitude install lvm2 I would recommend people trying this, because is easier than it seems,Īnd will not take longer than ten minutes.īefore doing anything, it is needed download lvm2 package, I had two disks, so I decided to migrate the data from the old home to the mirror. Redundance in order to prevent data losing. ![]() Had to reinstall my Debian, so I decided to add a little bit of I usually have my home directory in a different partition.Last week I ![]()
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