エラーメッセージが頻繁に表示されていました（通常はIbusプリファレンスで非常に頻繁に発生し、他のカテゴリでもエラーが発生することはほとんどありませんでした）。そこで、LiveCDを使用して再インストールし、ルート（/）とスワップ（linux-swap）の新しいパーティションをフォーマットして作成しました。ただし、既存のホームパーティション（/ home）を選択しないという間違いを犯しました。実際、/ homeには特定のスペースを指定しませんでした。

（再）インストール後、古い/ homeパーティションをマウントし直すために何かを試みました。そして、これを行った後（または少なくとも私はそう思います）、すべてのubuntuパーティションがWindows（拡張）パーティション（/ dev / sda3）の下に表示されます。空のウィンドウ（NTFS）パーティション（下の図の195.1GBの/ dev / sda3）にubuntuをインストールしたためだと思いました。

残念ながら、元のubuntuのインストール後に撮影したスクリーンショットはありません。

私は、ubuntuパーティションをHDDのWindows NTFSパーティション（それらのいずれにも含まれない）と並べて配置したかったのです。そこで、ubuntuを再インストールしましたが、今回は未割り当て領域（上図では220.35GB）を選択してインストールしました。そして、既存のホームパーティションを/ homeとして選択しました（フォーマットボタンがオフになっています）。ただし、ubuntuパーティションはWindowsパーティション（/ dev / sda3）の下に表示されたままです。理由はわかりません。

（1回目と2回目のインストール後の/ dev / sda3のサイズの違いに注意してください。スクリーンショットを参照してください）。

さて、2つの質問があります。

1. How can I install ubuntu in the hdd along-side windows, without any dependency? (Note that the **temp** is a NTFS, which is another windows partition & I’m not sure why it is also brought under this extended partition).
   
2. How to make an exiting home partition (not directory) to be the default **/home** for ubuntu – after completing the installation (without using LiveCD i.e. from a Ubuntu terminal). I’m sure there are ways, but I guess they all assume **/home** to contain user info only & not the data.
    i. I am (understandably) unable to access the **dev/sdax** (**/home** partition) using **cd/cp/mv** commands. Without these, how can I backup my data before doing this?
    ii. When I mount the old home partition as **/home**, the user folder created in the new home (during install) is getting removed. I don’t mind this, but can I restore my old users from the old **/home** partition when I mount it. If so, how can I do so.
    iii. Somewhere while trying, I saw my home partition listed as **/media/<something>** in the **Files** window. What does it mean & how can I handle mounting in such cases.

注：すべてのデータは/ homeパーティションにあります。

2020年10月7日に編集します（@heynnemaへの返信として）。

@heynnema: Sorry about the delay. I didn’t want to reply until I have tried everything suggested & get something working (or, not working).

Thank you. Yes, your answer was (very) helpful in understanding why my Ubuntu partitions (which need to be primary) were showing under the Windows extended partition (which is a logical partition). In fact, I missed to notice that I already had 3 primary partitions in Windows. I knew the MBR & Windows(C:) partitions to be primary, but I missed to consider Windows RE tools to be another primary partition (and, I still don’t understand the reason why there should be one – as it still expects one to have a recovery image in an external drive).

And, Ubuntu is not my primary, Windows-10 is (for now).

I couldn’t try your suggestion, as I don’t have an external drive with that much empty space. That is why I had to try copying /home data via terminal and that’s why I had to mention that I was unable to access /dev/sdax/ (/home).

But I still have 2 questions.

1. When we install ubuntu using “Install along side of Windows” method, we’d still have the same problem of the No. of max. Primary partitions, right? Or, would it be handled internally, somehow?
2. Let’s say I format the entire drive & install Ubuntu first, how can Windows be installed properly (as Ubuntu would have already taken 3 Primary partitions)? Will it be the reverse of how it is now (or) Ubuntu doens’t have those limitations on the No. of Primary partitions? And, both Ubuntu & Windows would show under /dev/sda?.

Anyway, so I tried to live with my existing hardware & installed ubuntu again with a completely new /home space.

@walttheboss: Thank you. That was a neat trick with fstab. I get fascinated by these kind of tweaks, as they let me understand the underlying structure/code better.

I tried it, but somehow I couldn’t get my old users to work. I was also unable to access my 3rd-party applications - which I installed in /home/software, assuming I can always have them with me (I still think I’m right to assume). I will try your method next time I mess-up something (I’m sure I will, as that’s how I learn – mostly). So, I re-installed it completely.

I’m still interested in knowing tweaks/workarounds (if there are any) as an answer to my other questions.

Finally, @heynnema: Sorry, I don't have a check-mark icon next to your answer (see screenshot below). I’m also not sure if I should accept if I haven’t tried it (yet). However, I have up-voted (up-arrow) as I was able to do so.

@walttheboss: Sorry, I couldn't find a way to up-vote your answer.