Creating Large File Systems: EVMS sees no free space

  • 3733121
  • 20-Nov-2006
  • 30-Apr-2012

Environment

Applies to any Linux host with large storage devices on which large file systems are to be deployed and on which EVMS is available. In the specific case that led to this document, the storage was a 5TB device and the platform SLES9 SP3. Therefore, the following platforms are applicable:

Novell SUSE Linux Enterprise Server 10
Novell SUSE Linux Enterprise Server 9
Novell Open Enterprise Server (Linux based)

Situation

Instinct says use YaST Partitioner (or fdisk, etc) to create a partition and file system on a disk. These tools default to creating DOS style partitions. Using LBA addressing, the maximum partition size is 2^32 blocks. For 512 byte sectors (blocks) that permits a theoretical maximum partition size of 2TB (0.5kB * 4G). Instinct further suggests the use of larger sectors to get larger partitions but the better solution is to abandon the DOS partitioning scheme as being inadequate. Switching to something like EVMS for storage carving resolves the issue. However, if you have already created a DOS partition table, EVMS won't see any"free" space on the device, even if it is has no actual partitions. This document explains how to resolve that.

Resolution

On the Linux host, in the X desktop, while logged in as root:

  1. Start evmsgui
  2. Select the "Disks" tab
  3. Locate the disk of interest
  4. Right click on it
  5. Select "Remove segment manager from Object..." and follow the instructions, selecting the "Remove" and "OK" buttons in the subsequent dialogs - This removes the partition table
  6. Select the "Segments" tab
  7. Locate the disk of interest
  8. Right click on it
  9. Select "Create EVMS Volume..."
  10. Enter a name for the volume in the create dialog - This name will become the devname name for device
  11. Press "Create" then "OK"
  12. Select the "Volumes" tab
  13. Locate, by name, the volume you created at step 10/11
  14. Right click on it
  15. Select "Make File System..."
  16. Select a suitable file system, e.g. ext2/3
  17. Press "Next"
  18. Specify appropriate parameters (e.g. "Create Ext3 journal" in the case of ext2/3). With very large volumes on storage systems with redundancy neither bad block check option should be necessary
  19. Press the "Make" then "OK" buttons
  20. Press the "Save" button on the evmsgui toolbar - This applies all the changes entered so far
  21. Press the "Quit" button on the toolbar
There should now be a device, /dev/evms/ and it should be formatted with the file system specified at step 16. It should now be possible to mount the file system in the normal way, e.g.:

mount -t ext3 /dev/evms/groovybigdisk

The file system should now be mounted and accessible, you can verify it with df or mount, for example.

Additional Information

Configuring the host to mount the file system at system boot time is left as an exercise for the reader (see /etc/fstab). This document assumes EVMS is properly installed, configured and enabled at boot time.

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