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Problem creating partitions > 1TB

 
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Fialia
Occasional Contributor

Problem creating partitions > 1TB

I am trying to create 2 partitions approximately 3TB in size. I have a Linux-machine with a 2.6 kernel and x86_64 architecture. The filesystem type is ext3. According to the information I have found I should be able to create partitions at least 32 TB in size, yet I keep ending up with 1 TB partitions.

According to fdisk there are a certain number of cylinders available. When I create a partition, the default (and max) number of cylinders I can chose for the upper range is much lower than the total listed however. And no matter if I divide the default in 2 and create 2 same-size partitions, or if I create 1 partitions of all the cylinders, the resulting disk(s) are 1 TB.

What can cause this?
1 REPLY
Matti_Kurkela
Honored Contributor
Solution

Re: Problem creating partitions > 1TB

The traditional PC partition table (designed along with the IBM PC/AT in the 1980s) cannot handle disks that big. I seem to recall that the limit is somewhere at or above 1 TB size, so that's what you're hitting.

If you want to create something resembling traditional partitions, you must use GPT-style partitioning (what is called a "Dynamic Disk" in newer Microsoft Windows products). The "fdisk" tool cannot do this; you must use "parted" or some other tool.

You could also skip the traditional partitioning entirely and use Linux LVM.

For example, if your large disk is /dev/sdd, begin with:
pvcreate /dev/sdd
vgcreate /dev/sdd
vgdisplay

Pick a name for your volume group and use it in place of .

To create a logical volume (the equivalent of a partition) of 3 TB size, you can run:
lvcreate -L 3T

If you don't use the options of lvcreate to specify a different name, your first logical volume will be named /dev//lvol0, the next /dev//lvol1, and so on.

LVM is more flexible than partitioning: if you need more disk space in your logical volume, you can extend the LV beyond the limits of a single disk. If you use a filesystem that allows on-line expansion (like ext3), you don't even need to unmount the filesystem to expand it.

MK
MK