“to swap, or not to swap, that is the question”: definately swap Shakespeare
“to encrypt, or not to encrypt” (if it contains valuable data, encrypt)
“to lvm, or not to lvm” (well….)
because: one fine day, the user decides to open 1000x programs + serveral vms at the same time, why not right?
the system runs out of RAM AND SWAP space (it almost freezes, to death).
but behold!
instead of simply pulling the plug.
the admin decides to wait and work on device B, while device A is struggling to keep alive.
after aprox 15min… the kvm vm crashes (probably because it used the most RAM) while the other programs survive.
For some reason, the otherwise excellent Debian installer, per default decides to reserve only 1GByte of SWAP on an 1000GB SSD.
In past times, the rule of thumb was “at least half of RAM size”, would even go as far and say: make swap = RAM size, why not? SSD space and NVMe space are getting cheaper and faster, nothing worse then running out of RAM & SWAP space (system enters undefined behavior, not only GNU Linux, OSX too)
let’s change that to something like 30GB of swap.
per default the user (probably) has chosen to use lvm2 (logical volume management) + luks2 encryption.
gparted is a pretty nice gui based program, that can do resize of ext4 partitions nicely, but it can’t help with logical volume management.
# HAVE A FULL BACKUP OF THE HARDDISK IN QUESTION! # boot dwaves' live usb stick, or another live system # (it is Debian 10 based) # IdealLinux stick, already has those requirements installed su - root apt update apt install lvm2 cryptsetup # first thing: find the partition in question lsblk -fs # might help too alias harddisks='lsblk -o '\''NAME,MAJ:MIN,RM,SIZE,RO,FSTYPE,MOUNTPOINT,UUID'\''' # run the alias harddisks # look at the disk sizes... # which one is (probably) the partition in question? # found it? good, let's continue... # decrypt the partition cryptsetup open /dev/sda5 encrypted *** enter decryption password *** # make all volume groups active vgchange -ay 2 logical volume(s) in volume group "IdealLinux2021-vg" now active 2 logical volume(s) in volume group "toplap-vg" now active <- that's the one vgdisplay; # list all volume groups --- Volume group --- VG Name toplap-vg <- System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 3 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 0 Max PV 0 Cur PV 1 Act PV 1 VG Size <931.02 GiB PE Size 4.00 MiB Total PE 238340 Alloc PE / Size 238340 / <931.02 GiB Free PE / Size 0 / 0 lvdisplay; # list all logical volumes --- Logical volume --- LV Path /dev/toplap-vg/root <- the one to shrink down to 900GB LV Name root VG Name toplap-vg LV Write Access read/write LV Creation host, time toplap, 2022-05-17 03:48:56 -0400 LV Status available # open 0 LV Size 930.06 GiB Current LE 238096 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 254:3 --- Logical volume --- LV Path /dev/toplap-vg/swap_1 <- the swap that is too small, will increase to 30GB LV Name swap_1 VG Name toplap-vg LV Write Access read/write LV Creation host, time toplap, 2022-05-17 03:48:56 -0400 LV Status available # open 0 LV Size 976.00 MiB Current LE 244 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 254:4 # run a pre-resize filesystem check fsck -y -v -f /dev/toplap-vg/root # resize the root filesystem from 930GB to 900GB resize2fs /dev/toplap-vg/root 900G resize2fs 1.44.5 (15-Dec-2018) Resizing the filesystem on /dev/toplap-vg/root to 235929600 (4k) blocks. The filesystem on /dev/toplap-vg/root is now 235929600 (4k) blocks long. lvreduce -L 900G /dev/toplap-vg/root WARNING: Reducing active logical volume to 900.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce toplap-vg/root? [y/n]: y Size of logical volume toplap-vg/root changed from 930.06 GiB (238096 extents) to 900.00 GiB (230400 extents). Logical volume toplap-vg/root successfully resized. # post-resize filesystem check fsck -y -v -f /dev/toplap-vg/root lvextend -l +100%FREE /dev/toplap-vg/swap_1 Size of logical volume toplap-vg/swap_1 changed from 976.00 MiB (244 extents) to <31.02 GiB (7940 extents). Logical volume toplap-vg/swap_1 successfully resized. mkswap /dev/toplap-vg/swap_1 mkswap: /dev/toplap-vg/swap_1: warning: wiping old swap signature. Setting up swapspace version 1, size = 31 GiB (33302769664 bytes) sync; sync; sync; # reboot system shutdown -r now;
it worked?
free -m total used free shared buff/cache available Mem: 7647 838 5338 162 1470 6382 Swap: 31759 0 31759
possibly related Links:
also checkout:
cudos:
https://www.casesup.com/category/knowledgebase/howtos/how-to-shrink-an-lvm-volume-safely-on-linux
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