I know this place maybe isn't the best place to ask for help with this specific question, but I guess you can help.

I have a UEFI system with partitions arranged as follows:

# /etc/fstab: static file system information
# <file system> <dir>   <type>  <options>   <dump>  <pass>
# /dev/sda2
UUID=1839555a-70c8-4fec-8938-cfd7a16ecc6d   /           ext4        rw,relatime,data=ordered,discard,noatime    0 1

# /dev/sdb1
UUID=6d26afd2-cc3e-44a4-b5bd-ea209cd4343d   /home       ext4        rw,relatime,data=ordered,discard,noatime    0 2

# /dev/sda1
UUID=7628-D37A          /boot       vfat        rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro    0 2

# /dev/sdb2
UUID=f37bdb49-1d0f-4455-8f2d-559b923bfb40   /var        reiserfs    rw,relatime 0 2

# /dev/sdb3
UUID=96c1dbed-cf83-4a2e-9fc2-dcd9fa01a6bb   /tmp        reiserfs    rw,relatime 0 2

(note that this is my system's fstab)

now, here is some info about how these partitions are arranged and their sizes:  hardware:

SSD - 60Gb
HDD - 500Gb

/ - about 20Gb on  the SSD
/boot -  about 1Gb on the SSD

/home - about 100Gb on the HDD
/var - 10Gb on the HDD
/tmp - 1Gb on the HDD

That means that I have about 389 Gb of empty space on the HDD, I want to use 100~200Gb from those to install Windows for games but I also want to keep some space for installing Gentoo.

What would be the easiest way to install Windows? I don't want to put it on the SSD and won't use it for anything other than gaming, and I don't want to ruin my current Arch setup.

Also can use the same /tmp partition in Arch or Gentoo? or it isn't possible? Same question but with a swap partition (that is if I eventually have to use one).

BTW what about using a VM? is it worth it? I have 8Gb RAM and can easily get more...

And do you have any other recommendations?

2 Answers 2


You will have to re-size the /dev/sdb1 partition first. You can do that with gparted, and, since you have / on a different disk, you don't even have to do it from a live distro.

You will have to decide how to split the space freed-up between Gentoo and Windows, according to your needs.

(One reasonable question though is: why do you wish to install Gentoo? Wouldn't a VM suit your needs? Consider the superiority of VMs as compared to dual-boots: you may run them simultaneously, you may share folders without any problem, you can re-size the VM at will without difficult and dangerous disk operations, you can carry your VM installation to another pc, with another hypervisor, thanks to the OVA format, without any trouble ...).

When you have decided how much room you need for Windows, format that much space with NTFS (remember to install the ntfs-3g package in Arch). Now you can install Windows from the installation disk because Windows will be unable to recognize the ext4 filesystem, and thus will occupy only the NTFS partition on your HDD. For extra security, make sure you have already formatted to ext4 also the room you left for Gentoo (if you are not going to heed my call to install it in a VM), lest Windows should grab that too.

When this is done, your pc may not boot at all, or may boot only on Windows or Arch. To prepare for this, you must have previously downloaded a copy of Ubuntu to a USB stick, boot from that, choose Try Ubuntu without installing, then install Boot-Repair as detailed in the Ubuntu Man Pages, and run it as specified in the link. Normally, this is enough to fix most booting problems.

N.B.: you cannot pre-install Boot-Repair on the USB because, this being a live distro, changes are volatile.

  • I'll check out the VM option, do you think 8 GB RAM is enough? also does GPT have the same primary partition number restriction as MBR? (can I have more than 4 primary partitions on the same disk?)
    – wael
    Dec 1, 2013 at 16:07
  • @wael 8GiB is plenty, no problem. GPT has no restriction on primary partitions: all partitions are primary, and you can have at least 128 partitions. Dec 1, 2013 at 16:26

You can only have four primary partitions, but one of those can hold a number of extended partitions.

I want to use 100~200Gb from those to install Windows for games but I also want to keep some space for installing Gentoo.

You probably want primary partitions for Gentoo and Windows, but /home, /var, and /tmp can be in extended partitions. That makes three primary partitions on the HDD.

Also can use the same /tmp partition in Arch or Gentoo?

In theory you should be able to, since it is not supposed to be used for persistent storage.

However, I'm not sure why you need or want a separate partition for /tmp at all. Have a look at du -h /tmp -- it's probably never more than a few hundred megabytes. I'd ditch that scheme in the process of rearranging things and just use a regular directory in your root filesystem. I'd do the same with /var too -- it just seems like a waste of a partition. You certainly can't save any space that way, only lose it.

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