## Name

vfs_gpfs — gpfs specific samba extensions like acls and prealloc

## Synopsis

`vfs objects = gpfs`

## DESCRIPTION

This VFS module is part of the samba(7) suite.

The `gpfs` VFS module is the home for all gpfs extensions that Samba requires for proper integration with GPFS. It uses the GPL library interfaces provided by GPFS.

Currently the gpfs vfs module provides extensions in following areas :

- NFSv4 ACL Interfaces with configurable options for GPFS

- Kernel oplock support on GPFS

- Lease support on GPFS

`NOTE:`This module follows the posix-acl behaviour and hence allows permission stealing via chown. Samba might allow at a later point in time, to restrict the chown via this module as such restrictions are the responsibility of the underlying filesystem than of Samba.

This module is stackable.

## OPTIONS

gpfs:sharemodes = [ yes | no ]

  Enable/Disable cross node sharemode handling for GPFS.

  - `yes(default)` - propagate sharemodes across all GPFS nodes.

  - `no` - do not propagate sharemodes across all GPFS nodes. This should only be used if the GPFS file system is exclusively exported by Samba. Access by local unix application or NFS exports could lead to corrupted files.

gpfs:leases = [ yes | no ]

  Enable/Disable cross node leases (oplocks) for GPFS. You should also set the `oplocks` and `kernel oplocks` options to the same value.

  - `yes(default)` - propagate leases across all GPFS nodes.

  - `no` - do not propagate leases across all GPFS nodes. This should only be used if the GPFS file system is exclusively exported by Samba. Access by local unix application or NFS exports could lead to corrupted files.

gpfs:hsm = [ yes | no ]

  Enable/Disable announcing if this FS has HSM enabled.

  - `no(default)` - Do not announce HSM.

  - `no` - Announce HSM.

gpfs:getrealfilename = [ yes | no ]

  Enable/Disable usage of the `gpfs_get_realfilename_path()` function. This improves the casesensitive wildcard file name access.

  - `yes(default)` - use `gpfs_get_realfilename_path()`.

  - `no` - do not use `gpfs_get_realfilename_path()`. It seems that `gpfs_get_realfilename_path()` doesn't work on AIX.

gpfs:winattr = [ yes | no ]

  Enable/Disable usage of the windows attributes in GPFS. GPFS is able to store windows file attributes e.g. HIDDEN, READONLY, SYSTEM and others natively. That means Samba doesn't need to map them to permission bits or extended attributes.

  - `no(default)` - do not use GPFS windows attributes.

  - `yes` - use GPFS windows attributes.

gpfs:merge_writeappend = [ yes | no ]

  GPFS ACLs doesn't know about the 'APPEND' right. This optionen lets Samba map the 'APPEND' right to 'WRITE'.

  - `yes(default)` - map 'APPEND' to 'WRITE'.

  - `no` - do not map 'APPEND' to 'WRITE'.

gpfs:refuse_dacl_protected = [ yes | no ]

  As GPFS does not support the ACE4_FLAG_NO_PROPAGATE NFSv4 flag (which would be the mapping for the DESC_DACL_PROTECTED flag), the status of this flag is currently silently ignored by Samba. That means that if you deselect the "Allow inheritable permissions..." checkbox in Windows' ACL dialog and then apply the ACL, the flag will be back immediately.

  To make sure that automatic migration with e.g. robocopy does not lead to ACLs silently (and unintentionally) changed, you can set `gpfs:refuse_dacl_protected = yes` to enable an explicit check for this flag and if set, it will return NT_STATUS_NOT_SUPPORTED so errors are shown up on the Windows side and the Administrator is aware of the ACLs not being settable like intended

  - `no(default)` - ignore the DESC_DACL_PROTECTED flags.

  - `yes` - reject ACLs with DESC_DACL_PROTECTED.

nfs4:mode = [ simple | special ]

  Enable/Disable substitution of special IDs on GPFS. This parameter should not affect the windows users in anyway. It only ensures that Samba sets the special IDs - OWNER@ and GROUP@ ( mappings to simple uids ) that are relevant to GPFS.

  The following MODEs are understood by the module:

  - `simple(default)` - do not use special IDs in GPFS ACEs

  - `special` - use special IDs in GPFS ACEs.

nfs4:acedup = [dontcare|reject|ignore|merge]

  This parameter configures how Samba handles duplicate ACEs encountered in GPFS ACLs. GPFS allows/creates duplicate ACE for different bits for same ID.

  Following is the behaviour of Samba for different values :

  - `dontcare (default)` - copy the ACEs as they come

  - `reject` - stop operation and exit with error on ACL set op

  - `ignore` - don't include the second matching ACE

  - `merge` - bitwise OR the 2 ace.flag fields and 2 ace.mask fields of the 2 duplicate ACEs into 1 ACE

nfs4:chown = [yes|no]

  This parameter allows enabling or disabling the chown supported by the underlying filesystem. This parameter should be enabled with care as it might leave your system insecure.

  Some filesystems allow chown as a) giving b) stealing. It is the latter that is considered a risk.

  Following is the behaviour of Samba for different values :

  - `yes` - Enable chown if as supported by the under filesystem

  - `no (default)` - Disable chown

gpfs:syncio = [yes|no]

  This parameter makes Samba open all files with O_SYNC. This triggers optimizations in GPFS for workloads that heavily share files.

  Following is the behaviour of Samba for different values:

  - `yes`Open files with O_SYNC

  - `no (default)`Open files as normal Samba would do

## EXAMPLES

A GPFS mount can be exported via Samba as follows :

            [samba_gpfs_share]
    	vfs objects = gpfs
    	path = /test/gpfs_mount
    	nfs4: mode = special
    	nfs4: acedup = merge

## CAVEATS

Depending on the version of gpfs, the `libgpfs_gpl` library or the `libgpfs` library is needed at runtime by the `gpfs` VFS module: Starting with gpfs 3.2.1 PTF8, the complete `libgpfs` is available as open source and `libgpfs_gpl` does no longer exist. With earlier versions of gpfs, only the `libgpfs_gpl` library was open source and could be used at run time.

At build time, only the header file `gpfs_gpl.h` is required , which is a symlink to `gpfs.h` in gpfs versions newer than 3.2.1 PTF8.

## VERSION

This man page is correct for version 3.0.25 of the Samba suite.

## AUTHOR

The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.

The GPFS VFS module was created with contributions from Volker Lendecke and the developers at IBM.

This manpage was created by the IBM FSCC team