Dist-upgrading Ubuntu Server 18.04 located in remote site?

Bo Berglund bo.berglund at gmail.com
Sun Feb 6 23:32:37 UTC 2022


On Sun,  6 Feb 2022 16:08:14 -0500 (EST), Robert Heller <heller at deepsoft.com>
wrote:

>> Question #1:
>> ------------
>> Is it safe to do a dist-upgrade via SSH (PuTTY from Windows) at a distance of
>> some 8500 km using OpenVPN?
>
>Probably.  So long as nobody yanks the power.  Is there noone local who can 
>babysit the machines?  

Well, it is a virtual machine inside a VMWare ESX system so it won't be subject
to any separate power fail. We had one the night of Saturday-Sunday, which
affected the RPi units, which restarted unexpectedly whereas the servers in the
VMWare system just continued running including my target server.

>> 
>> Question #2:
>> -------------
>> The /boot partition on this server is pretty small, just 472M with 72M freee
>> space...
>> I worry that it is not enough for what will happen on the dist-upgrade, so:
>> 
>> How can I safely remove all of the unused kernels to make space for new Ubuntu
>> 20 kernels?
>> Again doing this at a distance.
>> 
>> Info:
>> -----

I forgot to add the following command and result in my post:

$ uname -r
4.15.0-167-generic

So I am currently running 4.15.0-167-generic


>> This is what I see about the drives (removed the tmpfs entries):
>> 
>> $ df -h
>> Filesystem                         Size  Used Avail Use% Mounted on
>> udev                               461M     0  461M   0% /dev
>> /dev/mapper/vpnserver--vg-root      28G   15G   12G  55% /
>> /dev/sda1                          472M  376M   72M  85% /boot
>> 
>> So /dev/sda1 hosting /boot is the problem due to its small size...
>> 
>> And this is what ll lists:
>> 
>> $ ll /boot/
>> total 375518
>> drwxr-xr-x  4 root root     3072 2022-02-06 09:15 .
>> drwxr-xr-x 24 root root     4096 2022-02-06 09:14 ..
>> -rw-r--r--  1 root root   217432 2021-09-20 17:11 config-4.15.0-159-generic
>> -rw-r--r--  1 root root   217432 2021-10-15 08:16 config-4.15.0-161-generic
>> -rw-r--r--  1 root root   217432 2021-10-18 05:35 config-4.15.0-162-generic
>> -rw-r--r--  1 root root   217531 2021-12-08 11:15 config-4.15.0-166-generic
>> -rw-r--r--  1 root root   217531 2022-01-04 18:01 config-4.15.0-167-generic
>> drwxr-xr-x  5 root root     1024 2022-02-06 09:15 grub
>> -rw-r--r--  1 root root 60795727 2021-10-14 06:21 initrd.img-4.15.0-159-generic
>> -rw-r--r--  1 root root 60809700 2021-10-31 09:43 initrd.img-4.15.0-161-generic
>> -rw-r--r--  1 root root 60805485 2022-01-16 11:39 initrd.img-4.15.0-162-generic
>> -rw-r--r--  1 root root 60802475 2022-01-16 11:39 initrd.img-4.15.0-166-generic
>> -rw-r--r--  1 root root 60815651 2022-02-06 09:15 initrd.img-4.15.0-167-generic
>> -rw-r--r--  1 root root 15149612 2021-04-26 03:42 initrd.img-4.4.0-138-generic
>> drwx------  2 root root    12288 2018-02-23 13:23 lost+found
>> -rw-------  1 root root  4084049 2021-09-20 17:11 System.map-4.15.0-159-generic
>> -rw-------  1 root root  4084641 2021-10-15 08:16 System.map-4.15.0-161-generic
>> -rw-------  1 root root  4084622 2021-10-18 05:35 System.map-4.15.0-162-generic
>> -rw-------  1 root root  4085712 2021-12-08 11:15 System.map-4.15.0-166-generic
>> -rw-------  1 root root  4086497 2022-01-04 18:01 System.map-4.15.0-167-generic
>> -rw-------  1 root root  8453792 2021-09-20 17:25 vmlinuz-4.15.0-159-generic
>> -rw-------  1 root root  8453792 2021-10-15 08:19 vmlinuz-4.15.0-161-generic
>> -rw-------  1 root root  8453792 2021-10-18 05:37 vmlinuz-4.15.0-162-generic
>> -rw-------  1 root root  8461984 2021-12-08 10:53 vmlinuz-4.15.0-166-generic
>> -rw-------  1 root root  8466080 2022-01-04 18:13 vmlinuz-4.15.0-167-generic
>> 
>> Any suggestions/advice?

Meanwhile I found old notes on the way to free space in /boot so I have done
this:
1) List the available kernels:

$ dpkg --list 'linux-image*' | grep ^ii
ii  linux-image-4.15.0-159-generic          4.15.0-159.167 amd64        Signed
kernel image generic
ii  linux-image-4.15.0-161-generic          4.15.0-161.169 amd64        Signed
kernel image generic
ii  linux-image-4.15.0-162-generic          4.15.0-162.170 amd64        Signed
kernel image generic
ii  linux-image-4.15.0-166-generic          4.15.0-166.174 amd64        Signed
kernel image generic
ii  linux-image-4.15.0-167-generic          4.15.0-167.175 amd64        Signed
kernel image generic
ii  linux-image-generic                     4.15.0.167.156 amd64        Generic
Linux kernel image

Based on this I did:

$ sudo apt remove linux-image-4.15.0-159-generic
$ sudo apt remove linux-image-4.15.0-161-generic
$ sudo apt remove linux-image-4.15.0-162-generic
$ sudo apt autoremove

After this I got a new map:

$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
udev                               461M     0  461M   0% /dev
/dev/mapper/agivpnserver--vg-root   28G   14G   13G  52% /
/dev/sda1                          472M  205M  243M  46% /boot

/boot is now 54% free space...


>
>apt autoremove
>
>Then,
>
>apt purge linux-image-4.15.0-XXX-generic
>
>where XXX is the version number of the unused kernel(s) [159, 161, 162, and 
>166, assuming 167 is the running kernel]. 

I did not do the purge before but when I tried it now I got this after I also
did the remove for 166:

$ sudo apt remove linux-image-4.15.0-166-generic
$ sudo apt autoremove

$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
udev                               461M     0  461M   0% /dev
/dev/mapper/agivpnserver--vg-root   28G   14G   14G  50% /
/dev/sda1                          472M  135M  314M  30% /boot <==

$ sudo apt purge linux-image-4.15.0-159-generic
-- succeeded
$ sudo apt purge linux-image-4.15.0-161-generic
-- succeeded
$ sudo apt purge linux-image-4.15.0-162-generic
-- succeeded
$ sudo apt purge linux-image-4.15.0-166-generic
.....
Do you want to continue? [Y/n]
(Reading database ... 151431 files and directories currently installed.)
Purging configuration files for linux-image-4.15.0-166-generic (4.15.0-166.174)
...
I: /vmlinuz is now a symlink to boot/vmlinuz-4.15.0-167-generic
I: /initrd.img is now a symlink to boot/initrd.img-4.15.0-167-generic
rmdir: failed to remove '/lib/modules/4.15.0-166-generic': Directory not empty

Is the last message OK regarding non-empty directory?

This last purge set of commands did not change the state of the disk space
visibly by the df command.

>
>The 18.04 initrd.img files are 59M, the vmlinuz files are 8.1M and the System.map 
>files are 3.9M. The 20.10 (I don't have a 20.04 machine) file sizes are 59M 
>for the initrd.img file, 15M for the vmlinuz file, and 5.7M for the System.map 
>file. I am guessing that the 20.04 kernel files are similarly sized, so 
>freeing up one or two older kernels should free up enough disk space (and 
>freeing up 4 is even better).

As described above I also dealt with 166 and this brings usage down to 30% on
/boot.

>You should be sure to do 'apt full-upgrade' and reboot before doing the
>release upgrade.  And do 'apt autoremove'.

Yes, that will be the last step before actually running the relesae-upgrade...


-- 
Bo Berglund
Developer in Sweden





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