Hi there,
I would be very grateful for any help.
I have an 1 TB external HD, and would like to split it in two partitions through GParted.
I unmount the drive, etc. I get to reduce the size of the drive to, let’s say, 600 GB. Now I create another partition, allocating it with the remaining space.
When I try to run all changes, GParted ends with an error, saying that there are “too many primary partitions”. But even this I can’t change.
What am I doing wrong, please?
Thanks in advance.
If this is a disk with msdos partition table, you cannot have more than 4 primary partitions on it.
https://wiki.archlinux.org/title/Partition#Master_Boot_Record_(partition_table)
also may need to reboot if you are not on msdos partition table.
Well, I don’t think that is a msdos partition. Moreover, I have erased everything, “starting from scratch”. Just one partition, now, in nffs. I just can’t split it. 
have you tried using a gparted from a live ISO? Could be an issue with gparted on your system.
If you don’t have any data on the disk, you could try creating a new partition table.
Beware that if you have any data on the disk, creating a new partition table will wipe it out.
@pebcak is right. If this is for strictly data and no OS, then create a new GPT partition table.
Don’t try to make a single partition then split it in half. Just make 2 partitions to start with.
Pudge
Hey guys,
Thank you very much. 
I got to create a new partition and a partition table through parted, mklabel, etc. I really don´t understand why I was not able to do that through GParted.
But, from now on I got to use GParted to split in two.
Hey guys,
Do you know if I can have just one of the partitions in a external drive as a bootable one?
For example, I have now 2 partitions in that HD. But when I try to flash an ISO to it, BalenaEtcher, for example, gives me only the option to use the entire drive. Is it possible to use just one of the partitions?
what do you mean flash? Do you mean burn it to the drive? or do you mean install it to the drive?
So, I am trying to burn it to the drive.
But when trying to do that, the software gives me only the option to use the entire disk, and not just one of the partitions. Well, I don’t know if that is possible.
Are you trying to install an operating system to that partition?
If so, you cannot use Etcher.
You need to be more explicit and give as much info as possible when asking for assistance.
you don’t burn an ISO to a hard drive. You install it to a hard drive. You need to burn it to a USB to install it on the System.
Sorry guys, My bad. Maybe I don’t expressed very well what I need.
So, what I want to do is to use one of that partitions (in an external USB drive) for “image backups” through Rescuezilla (which is provided in a ISO format).
This is the ISO (Rescuezilla) I want to save in one of the partitions. But Etcher just gives me the option to use the entire drive.
You would need to run Rescuezilla off of a USB flash drive and then make your backups of whatever partitions you need to, in the format you want and save them to that partition.
Thank you.
I thought there was a way to “simulate” a pendrive through a partition in an external USB HD.
Maybe look at ventoy to boot, and it can load rescuezilla, amongst other ISOs, for you.
This is a bad idea you can just simply copy the ISO to the secondary partition.
Or Maybe you misunderstand how Rescuezilla works. Rescuezilla is not run on the drive your backing your Image files to.
If you want to put multiple ISO’s on a Thumb Drive then as @samarium stated you would want Ventoy.
Once you are running the Rescuzilla application it should find the partitions. IF its only giving you and option to use one partition then you need to look at the space of the Image file needs to be stored. So if you are cloning 512 GB then you need a minimal of 512 GB to clone to.