Extended partition deleted during installation

JSM · 2021-04-26 01:10

A few days ago I installed Q4OS as a second system to test.

I have a Lubuntu on sda1. And there was an extended partition on sda2 with about 1.2 GB. There are the entries for the logical drives (home, documents, etc.), as far as I know.

I reduced sda1 by 50GB with gparted (live USB) and formatted the 50GB with ext4, it was then sda3.

When installing Q4OS I chose sda3 as the installation partition. I refused swap partition, because I work with swapfile on the installation sda. The installation was successful and I have a start menu in Grub2 with Lubuntu and Q4OS.

But as I can see, the extended partition is gone. Nevertheless, my home works without any problems, both in Lubuntu and in Q4OS.

I do not get it. What happened? Why does it work without an extended partition? Or is the extended partition somehow "hidden" in gparted or GNOM disk?

bin · 2021-04-26 05:52

sda1 would be a primary partition.
The other logical drives live in an extended partition - sda2
You say logical drives as opposed to drive - what are they?

You reduced the primary partition by 50gb and created sda3 - which would be another primary partition.
So you now have 2 primary ptns with 2 different OS looking at the same extended partition.
In that case sda1 and sda3 would both see sda2 as the extended ptn and sdax as the logical drives.

All this sounds OK so far - however you may find things a little awkward having 2 different systems accessing the same data and config areas. There is room for some files to be overwritten, and 'Open Recent' can become a nightmare.

Simple way to do check what you are seeing would be to look at the drives as shown in a df command. The /dev/sdax that contains your Home should be the same in both OS

JSM · 2021-04-26 14:33

No, the problem is that when installing Q4OS on sda3, the extended partition on sda2 was obviously eliminated! It no longer exists. Still, both of my / home work correctly on both sda1 and sda3. I don't use a data partition because I have extremely little data on the hard disk.

When installing Q4OS, I assigned the sda3 to the installer. This also worked and Q4OS is installed on sda3 and is running correctly. Lubuntu on sda1 also continues to run correctly.

I therefore suspect that the installer deleted the extended partition sda2 and integrated it into sda3. That would of course not be very "nice" :-)

Yesterday I made the sda1 smaller again in order to install and test another Linux. Gparted did this correctly and named the new partition sda2. So it is clear that the extended partition was gone.

From the installation of Lubuntu I still had a swap partition, which I no longer use. It is 1.1 GB and I have now released (deleted) it. Can I define this space as an extended partition and then assign it to sda1, sda2 and sda3? Then all 3 primary partitions would have the same extended partition. Does it work? I would need clear instructions, but haven't found any with google.

Attached is a print screen from GNOM disk with the status of my partitions. If you add all the volumes, the result is actually 160 GB, so it is not "hidden" :-)

No, attachment is not working. Maybe because I am new? :-) But there are 3 primary partitions and then the free space of 1.1 GB. Nothing more.

Last edited by JSM (2021-04-26 14:38)

q4osteam · 2021-04-26 15:15

@JSM
Please provide more info about Q4OS installation, see https://www.q4os.org/forum/viewtopic.php?id=3502

JSM · 2021-04-26 15:54

USB stick with

sourceforge.net/projects/q4os/files/stable/q4os-3.14-x64-instcd.r4.iso

Trinity

Full

I think that I either overlooked an option in the installer that affects an already existing extended partition. Or if this option doesn't exist, the installer does something by default that it shouldn't. I didn't find anything about this in the installing instructions.

Apparently Linux doesn't need an extended partition. It's good :-). I just wonder how the extended partition disappeared during installation. It belonged to sda1 and I only specified sda3 for installation.

Attachments:

snapshot1.png, Size: 53.09 KiB, Downloads: 421

aluma · 2021-04-26 17:46

Essentially, an extended partition is a record in one initial sector of the hard disk. It is needed when the number of partitions exceeds the number 4 limited by the MBR.
There is no secret, you just need to count the number of partitions before and after the installer.

JSM · 2021-04-27 00:33

@aluma

The question in this topic is why an already existing extended partition (sda2) of Lubuntu (on sda1) disappeared when I installed Q4OS in sda3.

BEFORE I did the installation, I had resized the sda1 with a live USB with gparted in order to create another partition for the installation of Q4OS. I have created a new partition in the free space (ext4) and gparted called it sda3. This shows that Lubuntu's extended partition on sda2 still existed at this point in time.

Then I started the installation, with another live USB. There I assigned the sda3 to the installer and refused to create a swap partition. The installation was successful.

But the next time I looked at the drive with GNOM diks, the extended partition sda2 was missing. Apparently it was deleted during the installation of Q4OS on sda3 and the storage space was allocated to sda3. I can see this from the fact that sda3 now has 54GB. But I only cut off 50GB from sda1. The sda2 was 1.2GB. That fits pretty well.

As you have seen, I have cut off part of the sda1 again in the meantime, this time 40GB. This is how the current partitioning came about. The 1.1GB free space used to be an sda5 swap partition that is no longer used because I am using swapfile.

I posted this topic because I suspect the Q4OS installer took the sda2. Or that I ignored an advanced setting.

In case it was an advanced setting that I overlooked, it's not a problem. My mistake. But if it is the installer, then this has to be patched, because in any other case than mine there could be major data loss. If there had been a Windows on the sda1 and the extended partition was deleted, then the system will probably no longer work, I suspect.

So it's about finding out whether the installer is working properly and whether the options are well chosen. I didn't see any options to "extended partition". I think there should be the following:

1. Use existing extended partition
2. Create a new extended partition
3. Do not use an extended partition

Under no circumstances may the installer use or delete a partition that has not been assigned to him, not even the extended one.

Hope it is now more clear :-)

aluma · 2021-04-27 06:47

HI JSM

I'll try to explain, but English is not my native language ...

Partition is a physical area of a disk with its own file system, data, and so on.
An MBR can only address 4 such partition .
An "extended partition" is an add-on "interface" to the MBR to overcome this limitation.

Therefore, if the number of partitions during installation does not exceed 4, the installer has chosen the best option without an additional "interface". Physically, the partitions remain the same.

Regards.

Last edited by aluma (2021-04-27 06:49)

q4osteam · 2021-04-27 08:20

@JSM
Of course, the installer mustn't alter any partitions unwittingly. Q4OS uses Debian installer almost unmodified, so if the installer do so, it's almost certainly upstream Debian, and need to say just critical, bug. However, we really doubt the installer has removed your partition, as this Debian installer is tested and used heavily. A hardware fail or user mistake would be much more probable.

Anyway, thanks for reporting. We will try to exactly reproduce the configuration you described and follow the steps and try to reproduce this issue.

JSM · 2021-04-27 15:42

@Q4OS TEAM

Thanks!

I will soon install the Q4OS as my main system on sda1 and thus go through the installation process again. Maybe I'll see something there that I missed the first time. I'll post it here in a few days.

But it is good if you try the same.

I suspect that Lubuntu's extended partition was not used for / home, but only for the swap partition. That could be the reason why there are no problems with Lubuntu after the extended partition disappears. But it only has a few more days to "live" :-)

JSM · 2021-04-28 02:41

@Q4OS TEAM

Ok, I did the installation again, on sda1. I used the same ISO as the first time.

To create at least similar conditions, I first created an extended partition sda2, with gparted. See attachment "partition 1".

Installation information:

1. Classic install

2. Partition disk: Manual
Only 2 partitions were shown, sda1 and sda3.

3. I chose sda1 and set it up like this:

Use as: Ext4 journaling file system
Format prt: yes
Mount point: /
Mount options: default
Laben: none
Reserved blocks: 5%
Typical usage: standard
Boot table flag: off

4. In the "last chance" window everything was ok, only sda1 operations were mentioned.

5. I refused Swap Space

The installation ran without any problems.

In the next post the results ...

Attachments:

partition1.png, Size: 47.05 KiB, Downloads: 421

JSM · 2021-04-28 02:58

@Q4OS TEAM

In the attachment "partition 2" you can see that the extended partition sda2 no longer exists and is only available as free space (2.5GB). So the same as with the first installation, you can see the free space there (1.1GB) on the far right. The free space was not integrated into sda1. I was wrong on this point.

Obviously, the existing extended partition will be deleted and converted into free space.

There was a second effect on the Grub2. The menu has of course been adapted. However, the entry for sda3 has been changed. The menu settings are also apparently overwritten. When starting Q4OS on sda3, a long list of commands came up first ... then it started normally and correctly. It would be better if the installer gave a choice of whether to install the grub or not. And when you install it, you should only create an additional menu entry, you don't need to change the settings.

Ok, I hope the test helps. I have now installed Q4OS 3 as base on sda1 and will expand it for myself. But first I'll wait for the answer in the other topic. Q4OS 4 has higher system requirements (1GB Ram). This is what i have. Maybe it is deeper with Trinity? That would be great :-)

have a good night :-)

Attachments:

partition2.png, Size: 44.47 KiB, Downloads: 463

bin · 2021-04-28 05:48

You've created an extended partition, but by the look of it you have not then created a logical drive inside that partition. It is therefore ignored and that is why your installer only displays sda1 and sda3.

Attachments:

ksnip_20210428-054735.png, Size: 90.15 KiB, Downloads: 410

JSM · 2021-04-28 13:38

@bin

You still don't understand the problem :-( The installer has deleted the extended partition. It does not matter whether a logical drive was created there or not. The existing extended partition must not be used, changed or removed by the installer, because it can belong to another installation, for example a Windows.

Last edited by JSM (2021-04-28 13:38)

aluma · 2021-04-28 13:54

There is no file system, hence there is no physical partition. And therefore there is no point in recording MBR, because there is nothing to record.

bin · 2021-04-28 15:29

JSM wrote:

@bin
You still don't understand the problem :-( The installer has deleted the extended partition. It does not matter whether a logical drive was created there or not. The existing extended partition must not be used, changed or removed by the installer, because it can belong to another installation, for example a Windows.

I think I see your problem.

Look at the attached and you'll see how gparted and gnome-disk utility display information about the same disk.

Using gparted the 2 gb ptn was created as an extended partition, but no logical drive created and so gparted shows it as Unallocated

Gnome Disk reads it differently and so gives the 'wrong' impression, but the installation process recognises the gparted view of the disk - which is I think the more correct one.

Hope this helps.

Last edited by bin (2021-04-28 15:30)

Attachments:

snapshot1.png, Size: 86.86 KiB, Downloads: 410

JSM · 2021-04-28 15:49

@bin

Definitely not, as you can see from my two attachments :-) In the first one, the extended partition with GNOM Disk is displayed correctly. After the installation it no longer exists, second attachment. The storage space remains the same, the formatting as an extended partition has been deleted. That's how it is.

Now we want to wait until Q4OS TEAM has done its tests.

Last edited by JSM (2021-04-28 15:49)

aluma · 2021-04-28 19:38

Ok, we have an empty extended partition without logical partitions.
What options to the mount command should I specify so that my os (and the installer of Q4os) could "see" this section?

JSM · 2021-04-28 23:13

@aluma

It's not what the installer can see, but why it removed the extended partition. An extended partition, created and formatted, is basically a special form of partition with special usage. The extended partition, which serves as a container for logical partitions, can contain important data that is required by other operating systems. Therefore, the installer must not delete the extended partition even if it is empty at the time of installation. The installer simply does not have to touch the extended partition unless there is an option in the installer to use an already extended partition. I haven't found such an option. The installer only has to work with the primary partition assigned to it. Nothing more and nothing less.

q4osteam · 2021-04-28 23:53

We are not able to reproduce the issue in Virtualbox. We tried to follow the steps above as exactly as possible.
- Boot live media and partition disk with Gparted, see the first image
- Install Q4OS from the "q4os-3.14-x64-instcd.r4.iso" media
- Use "sda3" for root ext4 filesystem, no swap
- Reboot to installed system, install "gnome-disk-utility" and check partitions
- Everything seems to be fine, see the second image

Would you suggest anything for us to reproduce the issue ?

Disk partitioned before installation:

The disk after installation:

JSM · 2021-04-29 02:21

@Q4OS TEAM

Well, I tested it again. And for whatever reason, this time the extended partition was not deleted.

I made exactly the same entries as in the first two installations. The only difference the third time was that I only installed the minimal version of Q4OS (Ultimatly minimal desktop). I used "Full" for the first installation and "Basic" for the second. Both times the extended partition was deleted.

I got the ISO from here:

sourceforge.net/projects/q4os/files/stable/q4os-3.14-x64-instcd.r4.iso

Apparently it was updated 6 hours ago, but I used my already downloaded version:

Modified: 03/17/2021 2:40 PM

I notice that the installer looks much older than in your instructions for the live version. The graphics of my installer are very simple, for example without the world map:

https://dai-trying.com/tutorials/instal … e-desktop/

I also looked for this problem on debian:

https://bugs.debian.org/cgi-bin/pkgrepo … t=unstable

I did not find a corresponding error, but at least two similar ones, which show that the debian installer does not always handle existing data carefully.

https://bugs.debian.org/cgi-bin/bugrepo … bug=905793
https://bugs.debian.org/cgi-bin/bugrepo … bug=907955

Ok, so the only difference with the third installation was the installed version "Ultimatly minimal desktop".

I can't give you any further information. And I guess I'm not trying to install it again. Three times must be enough :-)

Here the printscreen before the installation as an attachment. Unfortunately the quality is a bit poor. Ksnapshot or my screen settings?

Attachments:

partition1.png, Size: 58.02 KiB, Downloads: 394

JSM · 2021-04-29 02:22

Here after (attachment)

Attachments:

partition2.png, Size: 55.42 KiB, Downloads: 383

aluma · 2021-04-29 06:10

Hi JSM

JSM wrote:

@aluma
...An extended partition, created and formated...

This is not true.
The logical drives inside the extended partition are formatted. As long as they are not there, the extended partition itself is equivalent to free space. There can be no Windows and you always create a new partition, primary or extended, in the place of this free space.

Regards/

Last edited by aluma (2021-04-29 06:10)

q4osteam · 2021-04-29 09:21

JSM wrote:

... Apparently it was updated 6 hours ago ...

Why do you think so ?
--

JSM wrote:

I got the ISO from here:
sourceforge.net/projects/q4os/files/stable/q4os-3.14-x64-instcd.r4.iso
Apparently it was updated 6 hours ago, but I used my already downloaded version:
Modified: 03/17/2021 2:40 PM

The image has not been updated definitely. You can see image's upload date "03/17/2021" in the SourceForge repository. You can easily verify your downloaded image using md5sum hash. The official Q4OS installation images are never modified, only new images with new names are released.

--

JSM wrote:

The only difference the third time was that I only installed the minimal version of Q4OS (Ultimatly minimal desktop). I used "Full" for the first installation and "Basic" for the second.

We have tried installation with Full as well as Basic profile, partitions still look fine. We would suspect a hardware, or hardware dependent, issue for your case. It would be helpful, if you would test the installation in Virtualbox and post a feedback. Anyway, thanks for reporting.

JSM · 2021-04-29 13:53

@Q4OS

I think it was updated because it says so on the sourceforge.net site. It's been 17 hours now. But maybe it only about the account?

I had an idea about the extended partition problem. It has been removed from Full and Basic, but not from Minimal. So it could be a script in Full and Basic, which removes the optional swap-space that you can select during the installation. Apparently no further operations are performed at Minimal.

Checks what exactly is happening with the swap-space option in the installer. It should be this:

1. If you don't agree, he doesn't do anything. If you agree, the installer should check whether an extended partition already exists.

2. If so, he should check whether there is a swap partition in it.

3. If both are so, then he should use the existing swap partition.

4. Otherwise, create a swap partition in the existing extended partition.

5. If there is no extended partition, he should look for free space and create it there, including the swap partition.

6. If no free space is found, the installer should use part of the primary partition to create the extended partition and the swap partition.

7. The exact information about these actions should be saved in a file on the primary partition.

8. After the installation, the reboot and the installation of one of the three desktop options, the file should be read and the operations of the installer should be reversed. Even with the Minimal Desktop.

9. Only the operations of the installer should be undone! This means that an extended partition that existed before the installation is not deleted, and neither is a swap partition.

10. If the installer has created an extended partition with part of the primary partition, you could try to append the space back to the primary partition. To do this, you would have to keep a script in the RAM, which executes this operation during shutdown. I don't know whether this is possible.

If this is too much effort, then you should simply remove the script that deletes the optional swap space :-)

Q4OS Forum

#1 2021-04-26 01:10

Extended partition deleted during installation

#2 2021-04-26 05:52

Re: Extended partition deleted during installation

#3 2021-04-26 14:33

Re: Extended partition deleted during installation

#4 2021-04-26 15:15

Re: Extended partition deleted during installation

#5 2021-04-26 15:54

Re: Extended partition deleted during installation

#6 2021-04-26 17:46

Re: Extended partition deleted during installation

#7 2021-04-27 00:33

Re: Extended partition deleted during installation

#8 2021-04-27 06:47

Re: Extended partition deleted during installation

#9 2021-04-27 08:20

Re: Extended partition deleted during installation

#10 2021-04-27 15:42

Re: Extended partition deleted during installation

#11 2021-04-28 02:41

Re: Extended partition deleted during installation

#12 2021-04-28 02:58

Re: Extended partition deleted during installation

#13 2021-04-28 05:48

Re: Extended partition deleted during installation

#14 2021-04-28 13:38

Re: Extended partition deleted during installation

#15 2021-04-28 13:54

Re: Extended partition deleted during installation

#16 2021-04-28 15:29

Re: Extended partition deleted during installation

#17 2021-04-28 15:49

Re: Extended partition deleted during installation

#18 2021-04-28 19:38

Re: Extended partition deleted during installation

#19 2021-04-28 23:13

Re: Extended partition deleted during installation

#20 2021-04-28 23:53

Re: Extended partition deleted during installation

#21 2021-04-29 02:21

Re: Extended partition deleted during installation

#22 2021-04-29 02:22

Re: Extended partition deleted during installation

#23 2021-04-29 06:10

Re: Extended partition deleted during installation

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Re: Extended partition deleted during installation

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