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Can't create a Partition greater than 2 terabytes

This document (3227298) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10

 

Situation

RAID5 configured as a single device greater than 2 terabytes (TB) in size
SLES 10 x86_64 was installed with a 30 GB root and left the rest of the disk available for one large partition.

In the Partitioner utility in YaST, the entire drive was visible.

After creating a Primary Partition with the rest of the disk space and use ext3 file system, the volume appeared to create and mount fine. Data could be copied the partition just fine.

But coming up after a reboot, fsck said that the superblock was corrupted. If you commented out the partition in /etc/fstab the server would then boot. After booting if you go into parted (and also Partioner) and it showed the partition as 262GB and it would no longer mount.

This procedure could be duplicated for the xfs filesystem as well.

Resolution

Reconfigure the RAID5 to present the multiple LUNs, each smaller than 2 TB.

 

Additional Information

Even though the OS Kernel may be a 64-bit, and LVM/EVMS supports a 64-bit filesystem, the Master Boot Record (MBR) for each device is limited to FFFFFFFFh (32 bits) sectors. FFFFFFFFh will only address a maximum of 2 TB.

The partition table in the MBR consists of 4 entries, each with:

1) A 32 bit field for the partition's beginning sector number
2) A 32 bit field for the partition's size (number of sectors)

The beginning sector number of the first partition is assigned based on disk geometry. The beginning sector numbers of subsequent partitions are calculated by adding the previous partition's beginning sector to the previous partition's size. The sum of these two numbers cannot exceed FFFFFFFFh. If the sum overflows the 32-bit field, the high order bits are truncated resulting in a beginning sector address that points into the middle of one of the previous partitions, causing an overlap.

If you create partitions from the command line using parted on a device that has a capacity greater than 2 TB, you will be protected from exceeding FFFFFFFFh, but you will not be able to use the space over 2 TB.

If you create multiple partitions in YaST using Partitioner that exceed 2 TB, it will appear that you are able to create them, but it will result an overlap.
If you create a single partition in YaST using Partitioner that exceeds 2 TB, it will create a valid partition which is 2 TB smaller than expected.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:3227298
  • Creation Date: 16-Nov-2006
  • Modified Date:23-Feb-2021
    • SUSE Linux Enterprise Desktop
    • SUSE Linux Enterprise Server

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