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Arun Kumar for AWS Community Builders

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How to increase/decrease FileSystem under LVM

Steps

a. Before starting, ensure the following packages are installed

e2fsprogs
lvm2
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b. Run pvdisplay to check which EBS is under LVM.

sudo pvdisplay
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c. Run vgdisplay to check unallocated space available for a volume group

sudo vgdisplay
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d. Find the lvm fs that you want to increase/decrease.

sudo lvscan
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e. Example: Increase vol17 size from 5Gb to 15Gb

>>lvextend -L15G /dev/vgs1/vol17 --resizefs
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f. Example: Reduce vol17 size from 5Gb to 1Gb ( you can only do this if no process is holding to the fs. Best is to unmount the fs)

  • Important to ensure package e2fsprogs is installed, else the below command can cause superblock/partition table corruption.
>>lvreduce -L1G /dev/vgs1/vol17 --resizefs
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g. If the EBS is resized, then need to do the following, example /dev/xvdg was resize from 950Gb to 1150Gb

lsblk
> growpart /dev/xvdg 1
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h. Resize the physical volumes using the pvresize command.

pvresize /dev/xvdg1
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i. Use vgdisplay to see the increased free size. To see what fs type that the LVM fs is run,

lsblk -f
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j.
i. If you are restoring an EBS snapshot with LVM, after mounting the restored EBS volume, then you need to do the below.

sudo yum install lvm2 (if lvm command not found )
sudo vgchange -ay
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ii. If doing pvdisplay shows an unknown physical volume, then run command

vgreduce — removemissing <VG NAME>
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k. To increase swap space under LVM, do the following

>>swapoff -v /dev/vgs1/vol54swap
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Disable the vol that contain the swap, might need to stop appls if swap is in-use and free memory not available.

>>lvextend -L32G /dev/vgs1/vol54swap
>>mkswap /dev/vgs1/vol54swap
>>swapon -va
>>cat /proc/swaps
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l. If the disk increased is greater than 2Tb and is using MBR partition type, you need to convert to GPT partition type.

gdisk /dev/nvme1n1
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[https://superuser.com/questions/1250895/converting-between-gpt-and-mbr-hard-drive-without-losing-data]

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