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vfs_aio_pthread(8) [centos man page]

VFS_AIO_PTHREAD(8)					    System Administration tools 					VFS_AIO_PTHREAD(8)

NAME

       vfs_aio_pthread - implement async I/O in Samba vfs using a pthread pool

SYNOPSIS

       vfs objects = aio_pthread

DESCRIPTION

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

       The aio_pthread VFS module enables asynchronous I/O for Samba on platforms which have the pthreads API available, without using the Posix
       AIO interface. Posix AIO can suffer from severe limitations. For example, on some Linux versions the real-time signals that it uses are
       broken under heavy load. Other systems only allow AIO when special kernel modules are loaded or only allow a certain system-wide amount of
       async requests being scheduled. Systems based on glibc (most Linux systems) only allow a single outstanding request per file descriptor
       which essentially makes Posix AIO useless on systems using the glibc implementation.

       To work around all these limitations, the aio_pthread module was written. It uses a pthread pool instead of the internal Posix AIO
       interface to allow read and write calls to be process asynchronously. A pthread pool is created which expands dynamically by creating new
       threads as work is given to it to a maximum of 100 threads per smbd process. To change this limit see the "aio num threads" parameter
       below. New threads are not created if idle threads are available when a new read or write request is received, the new work is given to an
       existing idle thread. Threads terminate themselves if idle for one second.

       Note that the smb.conf parameters aio read size and aio write size must also be set appropriately for this module to be active.

       This module MUST be listed last in any module stack as the Samba VFS pread/pwrite interface is not thread-safe. This module makes direct
       pread and pwrite system calls and does NOT call the Samba VFS pread and pwrite interfaces.

EXAMPLES

       Straight forward use:

		   [cooldata]
		path = /data/ice
		aio read size = 1024
		aio write size = 1024
		vfs objects = aio_pthread

OPTIONS

       aio_pthread:aio num threads = INTEGER
	   Limit the maximum number of threads per smbd that will be created in the thread pool to service IO requests.

	   By default this is set to 100.

VERSION

       This man page is correct for version 4.0 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.

Samba 4.0							    06/17/2014							VFS_AIO_PTHREAD(8)

Check Out this Related Man Page

VFS_TSMSM(8)						    System Administration tools 					      VFS_TSMSM(8)

NAME

       vfs_tsmsm - VFS module for handling offline files with Tivoli Storage Manager Space Management

SYNOPSIS

       vfs objects = tsmsm

DESCRIPTION

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

       The tsmsm VFS module is an extension for handling offline files with Tivoli Storage Manager Space Management.

       It tries to avoid calling expensive DMAPI calls with some heuristics based on the fact that number of blocks reported of a file multiplied
       by 512 will be bigger than 'online ratio' of actual size for online (non-migrated) files. If heuristic check fails, the module calls DMAPI
       and asks for a specific attribute which is present for offline (migrated) files. If this attribute presents, the file is considered
       offline.

       This module is not stackable.

OPTIONS

       tsmsm:hsm script = [ path to hsm script ]
	   hsm script should point to a shell script which accepts two arguments: operation and filepath. the tsmsm module only uses "offline" for
	   operation to set the file under filepath offline.

       tsmsm:online ratio = [ number ]
	   Ratio to check reported size against actual file size. The default value is 0.5.

       tsmsm:dmapi attribute = [ attribute-name ]
	   Name of a DMAPI attribute that is present when a file is offline. The default is "IBMobj" (which is what GPFS uses).

       tsmsm:dmapi value = [ value for the DMAPI attribute ]
	   Value that the DMAPI attribute should have for the file to be considered offline. The default is empty (no value required).

EXAMPLES

       A GPFS mount with TSM support can be exported via Samba as follows:

		   [gpfs_tsm_share]
		vfs objects = tsmsm gpfs
		path = /test/gpfs_mount

VERSION

       This man page is correct for version 4.0 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.

Samba 4.0							    06/17/2014							      VFS_TSMSM(8)
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