# Installation on 4TB drive **URL:** \ **Category:** RancherOS\ **Created:** [November 26, 2016, 2:02am UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717 "2016-11-26T02:02:07Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![konsumer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/konsumer/32/1882_2.png) [@konsumer](https://forums.suse.com/u/konsumer)\ **Post date:** [November 26, 2016, 2:02am UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/1 "2016-11-26T02:02:07Z")
I am having trouble installing RancherOS on a 4TB harddrive. I get it booted off thumb drive, and it installs correctly with `ros install`, but it’s only using 2TB of the 4TB harddrive. I get this message in fdisk: ```auto The size of this disk is 3.7 TiB (4000787030016 bytes). DOS partition table format can not be used on drives for volumes larger than 2199023255040 bytes for 512-byte sectors. Use GUID partition table format (GPT). ``` I think I need to use GPT, rather than MBR. I can’t seem to convert it after installation, which insists on MBR re-partitioning. I thought about using another drive to be the “boot drive” and partitioning the large drive for after boot, but it’s a small computer with only room for 1 harddrive, and I’d prefer to not have a thumbdrive poking out, if at all possible. I’d really like to use RancherOS, but I’m not sure how, in this scenerio. ---
**Author:** ![konsumer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/konsumer/32/1882_2.png) [@konsumer](https://forums.suse.com/u/konsumer)\ **Post date:** [November 26, 2016, 10:42pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/2 "2016-11-26T22:42:35Z")
If no one has any info on how to make `ros install` work with GPT, I bet I could cobble something together if I knew the files that need to be copied. Maybe I could manually partition, install grub, and copy the OS files? Where are those located? ---
**Author:** ![joshwget](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/joshwget/32/704_2.png) [@joshwget](https://forums.suse.com/u/joshwget)\ **Post date:** [November 28, 2016, 5:50pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/3 "2016-11-28T17:50:07Z")
`ros install` does a pretty standard manual install behind the scenes, so it’s definitely possible to do yourself. The installer script is located [here](https://github.com/rancher/os/blob/master/scripts/installer/lay-down-os) and that should be a pretty helpful reference. ---
**Author:** ![konsumer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/konsumer/32/1882_2.png) [@konsumer](https://forums.suse.com/u/konsumer)\ **Post date:** [November 28, 2016, 6:07pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/4 "2016-11-28T18:07:03Z")
Thanks! This does seem pretty straightforward. Maybe I could improve it to handle cases like mine ( “custom partition-scheme” CLI flag?) I ended up just installing a light ubuntu server (with GPT + BTRFS) and getting docker + rancher working on it. I will do it all manually, following the script, when I get home. I’d be happy to document the process for the wiki, if there’s interest. ---
**Author:** ![joshwget](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/joshwget/32/704_2.png) [@joshwget](https://forums.suse.com/u/joshwget)\ **Post date:** [November 28, 2016, 6:58pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/5 "2016-11-28T18:58:17Z")
We’re planning on reworking a lot of the installer for v0.8.0, so some notes on what you end up doing would certainly be appreciated! ---
**Author:** ![konsumer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/konsumer/32/1882_2.png) [@konsumer](https://forums.suse.com/u/konsumer)\ **Post date:** [November 28, 2016, 7:36pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/6 "2016-11-28T19:36:57Z")
I can’t be sure, but I think the `dd bs=440 count=1 if=/usr/lib/syslinux/mbr/mbr.bin of=${DEVICE}` is the part that is forcing the MBR partition scheme? On [these instructions](https://wiki.archlinux.org/index.php/syslinux#Boot_process_overview) I notice the bit about `gptmbr.bin` and wonder if it might make sense to simply detect the partition scheme before the `dd` call, or maybe adding a flag `-g` for “use GPT instead of MBR”. I’ll have to play with it when I get home. Is this a PR worth making, or is the rework going to be significantly larger that I shouldn’t bother? ---
**Author:** ![SvenDowideit](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/svendowideit/32/2159_2.png) [@SvenDowideit](https://forums.suse.com/u/SvenDowideit)\ **Post date:** [November 28, 2016, 10:57pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/7 "2016-11-28T22:57:23Z")
Yes, its always worth making a PR! Its very useful to know how other people use the tools we work on - otherwise we’re just writing code that we think will be useful! I do expect to be re-writing the installer in go this week - but at the moment, I’m fighting with aws, osx and windows home edition. ---
**Author:** ![konsumer](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/konsumer/32/1882_2.png) [@konsumer](https://forums.suse.com/u/konsumer)\ **Post date:** [November 29, 2016, 12:23am UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/8 "2016-11-29T00:23:13Z")
[here](https://github.com/konsumer/os/commit/251bc17b7fe48421bc7ad82c6c088f05706a7e9a) is the initial change, but I can’t test until I get home. What other scripts get run in `ros install`? I’d like to test all of them to make sure something else doesn’t clobber it. ---
**Author:** ![SvenDowideit](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/svendowideit/32/2159_2.png) [@SvenDowideit](https://forums.suse.com/u/SvenDowideit)\ **Post date:** [December 14, 2016, 1:48pm UTC](https://forums.suse.com/t/installation-on-4tb-drive/4717/9 "2016-12-14T13:48:49Z")
@konsumer raised a PR : [https://github.com/rancher/os/pull/1448](https://github.com/rancher/os/pull/1448) and I’ve made some additions to it, which once merged will get us part of the way there.