IBM General Parallel File System for AIX: Administration and Programming Reference

mmdeldisk Command

Name

mmdeldisk - Deletes disks from a GPFS file system.

Synopsis

mmdeldisk Device "DiskName[;DiskName...]" [-a] [-c] [-p] [-r] [-N {all | mount | NodeName[,NodeName ... ] }]

Description

The mmdeldisk command migrates all data that would otherwise be lost to the remaining disks in the file system. It then removes the disks from the file system descriptor and optionally rebalances the file system after removing the disks.

Run the mmdeldisk command when system demand is low.

If a replacement for a failing disk is available, use the mmrpldisk command in order to keep the file system balanced. Otherwise, use one of these procedures to delete a disk:

• If the disk is not failing and GPFS can still read from it:
  1. Suspend the disk
  2. Restripe to rebalance all data onto other disks
  3. Delete the disk
• If the disk is permanently damaged and the data cannot be recovered, delete the disk if the file system is not replicated. If the file system is replicated:
  1. Suspend the disk.
  2. Restripe and restore replication for the file system, if possible.
  3. Delete the disk from the file system.

     Later, when the disk is repaired or a replacement is available:

  4. Add the repaired or new disk back into the file system
  5. Restripe the file system

Note:

The mmdeldisk command does not delete a disk in a stopped state unless you specify the -p option. A stopped disk must be started before it can be deleted using mmdeldisk.

Results

Upon successful execution of the mmdeldisk command, these tasks are completed:

• Unreplicated data from the target disks is migrated to other disks in the file system.
• Remaining disks are rebalanced, if specified.

Parameters

Device

The device name of the file system to delete the disks from. File system names need not be fully qualified. fs0 is as acceptable as /dev/fs0. This must be the first parameter.

"DiskName[;DiskName...]"

The names of the disks to be deleted from the file system. Use the mmlsdisk command to display disk names. If there is more than one disk to be deleted, delimit each name with a semicolon (;) and enclose the list of disk names in quotation marks.

-N { all | mount | NodeName[,NodeName ... ] }

Specify the nodes which should participate in the restripe of the file system after the specified disks have been removed. Valid values are:

all

Indicates that all nodes in the GPFS nodeset, whether or not they have the file system mounted, should participate in the restripe. This is the default when the -N option has not been specified.

mount

Indicates that only the nodes which have the file system mounted should participate in the restripe of the file system.

NodeName[,NodeName ... ]

A comma-separated list of nodes that should participate in the restripe.

The hostname or IP address used for a node must refer to the adapter port over which the GPFS daemons communicate. Alias interfaces are not allowed. Use the original address or a name that is resolved by the host command to that original address. You may specify a node using any of these forms:

Format	Example
Short hostname	k145n01
Long hostname	k145n01.kgn.ibm.com
IP address	9.119.19.102

Options

-a

Specifies that the mmdeldisk command should not wait for rebalancing to complete before returning. When this flag is specified, mmdeldisk runs asynchronously and returns after the file system descriptor is updated and the rebalancing scan is started, but it does not wait for rebalancing to finish. If no rebalancing is requested (-r option is not specified), this option has no effect.

-c

Specifies that processing should continue even in the event that unreadable data exists on the disks being deleted. Data that has not been replicated is lost. Replicated data is not lost as long as the disks containing the replication are accessible.

-p

Indicates that the disks are permanently damaged or no longer accessible, and instructs the mmdeldisk command not to attempt to read any data or metadata from the disk. Instead of migrating the data, mmdeldisk invalidates all references to the deleted disks in the inodes and indirect blocks. Run mmfsck after using this option.

This option is valid only for a file system where replication has been set for metadata (see mmcrfs and mmchfs). Any subsequent request to read data from a file that was stored on a deleted disk and not sufficiently replicated returns an I/O error (EIO).

-r

Rebalance all existing files in the file system to make more efficient use of the remaining disks.

Exit status

0

Successful completion.

1

A failure has occurred.

Security

You must have root authority to run the mmdeldisk command.

In an SP environment:

1. Verify the authentication method set for SP security services:
   1. If your authentication method is set to compatibility, Kerberos authentication is required. Issue the k4init command.
   2. If your authentication method is set to DCE, dce_login authentication is required.
   3. If your authentication method is set to NONE/std, there must be an entry in the /etc/sysctl.mmcmd.acl file on every node in the nodeset for the root user at every other node in the nodeset.

   For further information, see the latest IBM Parallel System Support Programs for AIX: Administration Guide, IBM Parallel System Support Programs for AIX: Command and Technical Reference, and RS/6000: Planning Volume 2, Control Workstation and Software Environment manuals at www.rs6000.ibm.com/resource/aix_resource/sp_books/pssp. Search for information on sysctl.

2. You may issue the mmdeldisk command from any node running GPFS or the CWS.
3. If you are executing mmdeldisk from the CWS on a multi-partitioned system, the SP_NAME environment variable must be properly set. It is suggested that you use a separate window for each partition and set the environment variable accordingly. For further information, see the IBM Parallel System Support Programs for AIX: Administration Guide and search for understanding system partitioning.

In an HACMP environment:

1. When using rcp and rsh for remote communication, a properly configured /.rhosts file must exist in the root user's home directory on each node in the GPFS cluster. If you have designated the use of a different remote communication program on either the mmcrcluster or the mmchcluster command, you must insure:
   1. Proper authorization is granted to all nodes in the GPFS cluster.
   2. The nodes in the GPFS cluster can communicate without the use of a password.
2. You may issue the mmdeldisk command from any node in the GPFS cluster.

Examples

To delete gpfs2vsd and gpfs3vsd from file system fs0 and rebalance the files across the remaining disks, enter:

mmdeldisk fs0 "gpfs2vsd;gpfs3vsd" -r

The system displays information similar to:

Deleting disks ...
GPFS: 6027-589 Scanning file system metadata, phase 1 ... 
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-589 Scanning file system metadata, phase 2 ... 
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-589 Scanning file system metadata, phase 3 ... 
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-565 Scanning user file metadata ...
   6 % complete on Wed Aug 16 16:03:25 2000
 100 % complete on Wed Aug 16 16:03:27 2000
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-370 tsdeldisk completed.
mmdeldisk: 6027-1371 Propagating the changes to all affected nodes.
This is an asynchronous process.
Restriping fs0 ...
GPFS: 6027-589 Scanning file system metadata, phase 1 ... 
  76 % complete on Wed Aug 16 16:03:57 2000
 100 % complete on Wed Aug 16 16:03:58 2000
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-589 Scanning file system metadata, phase 2 ... 
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-589 Scanning file system metadata, phase 3 ... 
GPFS: 6027-552 Scan completed successfully.
GPFS: 6027-565 Scanning user file metadata ...
   6 % complete on Wed Aug 16 16:04:09 2000
 100 % complete on Wed Aug 16 16:04:11 2000
GPFS: 6027-552 Scan completed successfully.
Done
 

See also

mmadddisk Command

mmchdisk Command

mmlsdisk Command

mmrpldisk Command

Location

/usr/lpp/mmfs/bin