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Most of the time I have 2, 3 or more Linuxes (usually ubuntu-family) side by side and I want to limit the number of my partitions.

So, I only use / partition for each of them and never had problems. A home folder is present anyway and I do not see why that should be on a separate partition.

But I see that many people recommend almost as a necessity to have a separate /home partition.

I would see that as an advantage if it could be used for different systems at the same time or something like that, which, while doable, is not what I need, I think, as the home folder contains settings which are very system-specific and also program-specific and program-version-specific.

  • As far as settings are concerned: using an old home folder/partition with a new system seems useless or even dangerous to me.

  • As far as data files (multimedia, documents etc) are concerned: as indicated in a comment under this answer - a completely separate partition (outside any system installation) and possibly symlinks is a better choice: isn't it?

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  • 2
    Have you checked this post?
    – d a i s y
    Feb 21, 2017 at 11:46
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    Note that I have kept the same /home partition (and $HOME dir) across more than a dozen different installations, many including completely switching distributions. Yes, you can have problems but you can also have none. Why would you find it useless to not need to re-configure your favorite applications all over again?
    – terdon
    Feb 21, 2017 at 12:13
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    @cipricus heavy? Most configuration settings are just simple text files. Those are negligible when discussing disk usage. And no, gtk and qt have their own separate settings and most apps have theirs in ~/.appname or ~/.config/appname so, again, there's no reason for conflicts. And no, I don't tend to multi-boot these days but I used to back when I was distro hopping more often and yes, I would share the same /home and sometimes same /home/$user across the multiple systems. Of course today this is all solved by using GPT instead of MBR: limitless partitions!
    – terdon
    Feb 21, 2017 at 12:40
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    @cipricus that answer is just the user's opinion with no backing evidence. I've done this, and done it often, and it usually works fine. Yes, sometimes the file format or whatever has changed but then you just delete the conf file and use the default which will be recreated when you open the application. You just also need to remember than anything you change on one system, will also be changed on the other (say your vlc setting or whatever).
    – terdon
    Feb 21, 2017 at 12:46
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    @marcelm i) ease of migration; ii) (minor) safety net: screwing up your /home partition can leave the / intact and vice versa. Absolutely not a necessity, no argument there, but I have very often had reason to be glad I had them separate. Oddly enough, I too have been using Linux for almost 20 years and had never had a separate /boot (until EFI) while always keeping separate /home. YMMV I guess :)
    – terdon
    Feb 21, 2017 at 14:31

4 Answers 4

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Personally, I don't have a "technical" answer to give you and I don't think that there is one (e.g. like say, separate partitions offer greater performance), but I have always been using separate partitions for my /home folder and the main reason is the one you mention: keeping my customization and settings intact after a clean install. Especially with KDE plasma, which is full of customization and personal settings, I wouldn't want to spend two days setting the environment up, every time I did a fresh install. I can see why that might be the cause of future problems, but I weigh the pros and cons and I always choose to use a separate /home. Additionally, as izx mentioned here :

  • The biggest pro, in my opinion, is that you can easily install a newer Ubuntu version (or any Linux distro for your architecture, really), without losing most of your custom settings, configurations, downloads, etc., since such a step usually involves wiping out the existing system/boot partitions. You simply choose to preserve your /home in the partitioner during install, and you're set.
  • It is also possible to do this with /home on your / partition, but is a little more complicated. It also makes resizing/migrating to a larger home partition easier, if you ever need more space.
  • It isn't going to affect the speed of file access much, UNLESS you tend to have lots and lots of small files in your home directory. e.g., if you are a developer, or you have lots of sources lying around. That MAY affect overall file access speed on the entire partition with some filesystems. In that case, go for a separate /home.
  • There aren't any risks to making a separate home partition.

Another good reason is if, for some reason, you wanted to use a different disk for your /home folder. So to wrap it up, it's more a matter of choice and what you want to do with your system. I think it's safe to say, that it's perfectly fine to leave as it is with one big partition.

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    from your KDE experience: what about later using a system that doesn't need all the KDE settings, services for example? isn't the /home partition becoming heavy of useless stuff?
    – user47206
    Feb 21, 2017 at 12:27
  • "..., UNLESS you tend to have lots and lots of small files in your home directory ... In that case, go for a separate /home." - What? Why? I see no reason why that would help in the slightest. Can you elaborate?
    – marcelm
    Feb 21, 2017 at 13:14
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    "There aren't any risks to making a separate home partition." - Yes there are. Running out of space on one partition while the other still has room is a genuine problem and in most cases not easily fixed. Also programs that generate/receive a large file in /tmp and then move it to your home dir on completion will see a large performance hit when /tmp and /home live on different file systems.
    – marcelm
    Feb 21, 2017 at 13:17
  • This is a drawback yes, which can be solved (painstakingly some times), but as I said it is a matter of what you want to do with your system. On the other hand, in your /home folder the only thing that resides are configurations, so if you choose to uninstall some applications or services, the configurations may be still there, but they're not going to affect the responsiveness of your system, since they're just files, just sitting around. In some cases some of them might end up consuming a lot of space, so then you really need to put a hand under the hood and delete some stuff.
    – iraklis
    Feb 22, 2017 at 11:39
  • @marcelm I guess what izx is trying to say is that if you have many I/O with files, it could be easier/quicker for some filesystems to access these files if they lie in a separate partition. I would presume that it has to do with leaving / partition alone minding its own business while you are working with your files on /home, but tbh it's getting more technical than my filesystems understanding.
    – iraklis
    Feb 22, 2017 at 11:41
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It is safe
Nothing wrong with using only one root partition per install. It's the default way to do it, linking another partition is an option.

  • As far as settings are concerned: using different distros might indeed cause some clashes. It can be very annoying but not really dangerous since the settings are for user level apps.
    On the other hand, when doing an upgrade with the same distro or restoring a crashed system, keeping all your settings can save a lot of time, from your desktop background to your bookmarks, etc.

  • As far as data files: Symlinks are a good way to go about it, they just need to be setup. For someone using only one system, a separate home partition is in essence, similar to symlinks: your data is apart from your system.

Personally I use both.
The distro I use daily has a separate home partition, with the Videos, Music and Documents folders symlinked to a different drive. So I keep my home settings if I ever need to restore or upgrade and if I want to change my main distro entirely, I can compress all the hidden files and folders and restore the ones I want (firefox, etc) after the install.
I have another 3 distros installed, just for messing around. They have just one root partition each, and the same symlinks in their home folders. So I can easily access the data and not get setting problems.

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  • @Melebius - that's an error and I will correct it.
    – user47206
    Feb 21, 2017 at 14:34
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    Well I did mean it the original way. By "dissimilar", I mean distros that use different software (window manager, file browser, etc). Their settings are less likely to overlap and cause problems. While "similar" distros (yet different) will try to access the same setting files even tho they might be running different versions.
    – pevinkinel
    Feb 21, 2017 at 15:24
  • But to be fair, it's more of an educated guess on my part than some hard facts, so I'll remove that sentence altogether.
    – pevinkinel
    Feb 21, 2017 at 15:31
  • I always keep a separate home partition, and it is safer: in case / gets corrupted, you can reinstall the OS without loosing your home folder. Yes, I have had this happen to me. Yes, I should have had backups.
    – jpaugh
    Feb 21, 2017 at 17:33
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otherwise with let's say three Linuxes I would need 6 partitions already and that wouldn't fit an extended partition!

If I'm understanding you correctly, you're operating under a misapprehension. An extended partition can hold an arbitrarily large number of logical partitions. The exact limit depends on the size of the disk, but for any modern hard disk, the limit far exceeds six partitions. I've created test disks with something on the order of 100 logical partitions and that works fine. (That said, some older Linux distributions max out at, IIRC, 16 partitions per disk. Ubuntu has ways around that, though, as do most modern Linux distributions.) Many modern computers use the GUID Partition Table (GPT) partitioning system, which has a default limit of 128 partitions, and that limit can be raised if necessary.

But I see that many people recommend almost as a necessity to have a separate /home partition.

I would see that as an advantage if it could be used for different systems at the same time or something like that, which is not possible. The home folder contains settings which are very system-specific and also program-specific and program-version-specific.

It's possible, and safe, to share a /home partition between distributions. The trick is to ensure that users have different home directories on that shared /home partition. For instance, if you're sharing the /home partition between Ubuntu and Mint, you might give the user Fred the home directory /home/fred-ubuntu under Ubuntu and /home/fred-mint under Mint.

This is most easily accomplished by giving users different usernames in each distribution -- thus, Fred might use fred-ubuntu and fred-mint, depending on which distribution is being booted. You can, however, use the same username (say, fred) across distributions, but assign different home directories. Ubuntu's installer doesn't make this easy for accounts created at system installation time, but it can be accomplished by either renaming the home directory or changing the username after installing the OS. (Both tasks can be done with the usermod command, although renaming the home directory will also require using mv.) Some distributions enable customizing the home directory name at system installation time, which is helpful when setting something like this up.

With the separate home directories created, you can create symbolic links to simplify access -- for instance, you might have a symbolic link from ~/mint to ../fred-mint in the /home/fred-ubuntu directory to make it easier to access Mint files from Ubuntu; or you could link subdirectories you use (like ~/Downloads or ~/Videos) directly.

Setting things up this way does take more initial effort than creating separate /home partitions for each distribution, or not using separate /home partitions at all; however, it can make for more efficient use of space.

Stepping back further, though, IMHO installing multiple Linux distributions in a multi-boot environment is unlikely to be very helpful. If you want to learn about different distributions (say, RPM vs. Debian package management systems), running one distribution in a virtualized environment (VirtualBox, VMware, QEMU/KVM, etc.) can be quite effective and will save you from multi-boot headaches. If you simply want to try different desktop environments, these are not tied to whole distributions; you can install as many desktop environments as you like within one distribution and switch between them by logging out and back in again. You can even run different desktop environments simultaneously in different VTs, as described in this question and its answer.

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  • I removed the extended partition limitation statement. I appreciate that info as well as on symlinks. Although I cannot match your level of expertise, I cannot agree with your last statements: mingling desktops is one of the first errors I made in Linux and I will not go into that. I haven't found desktops that are good enough when used by themselves: only well tuned distros can make a desktop good enough for me. - And in order to compare distros (which means also DEs), multi-boot is the best thing for me. (VBox is killing my HP CPU but I have to agree it works just fine on a macbook).
    – user47206
    Feb 21, 2017 at 14:24
  • considering the sharing of the home partition between different systems: what's the point of doing that with different usernames? what will be shared then between the systems? and if no per-user setting is shared why use the same home partition? for space?
    – user47206
    Feb 21, 2017 at 14:43
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    Without knowing details, I can't comment on your problems with multiple DEs on a single distribution; but it's always worked fine for me. As to sharing a /home partition, if you don't want a separate /home partition, there is perhaps little point; but if you do want separate /home partition(s), sharing a single one is better for space management, since you don't need to worry about running out of space in Distribution A and having too much in Distribution B, which would necessitate moving files or resizing partitions if you used separate /home partitions.
    – Rod Smith
    Feb 21, 2017 at 14:55
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    An example of large number of logical partitions on an extended partition
    – phuclv
    Feb 21, 2017 at 15:40
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    it's also possible to use LVM for multiple logical volumes
    – phuclv
    Feb 21, 2017 at 15:51
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Reasonably safe. The main reasons to use separate partitions are:

1) Desire to use different filesystems, such as EXT3 for Boot and TMPFS for /tmp 2) The desire to use different permissions. I commonly have a separate /usr partition so that I can mount it Read-Only (bit of a paranoid anti-hack thing) 3) The desire to limit usage, such as mounting with noexec (common for /tmp, another paranoid anti-hack thing) 4) The desire to limit space without impacting other operations (/var so that /var/log filling does crash the system) 5) The need for different levels of redundancy (perhaps mirroring OS, but Raid 6ing general user data)

Biggest issue for putting everything under root is filling it accidentally (like with log files) and having all hell break lose.

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  • Having a full /var is usually as bad as having a full /. That is to say, not really a "hell", no.
    – kubanczyk
    Feb 21, 2017 at 21:24
  • Forgot one of the more important reasons to split filesystems up: limit the damage if one gets corruptions!
    – Cassey
    Mar 6, 2017 at 18:57