vfs_aio_linux - implement async I/O in Samba vfs using Linux kernel aio calls
vfs objects = aio_linux
System Administration tools VFS_AIO_LINUX(8)
NAME
vfs_aio_linux - implement async I/O in Samba vfs using Linux kernel aio
calls
SYNOPSIS
vfs objects = aio_linux
DESCRIPTION
This VFS module is part of the samba(7) suite.
The aio_linux VFS module enables asynchronous I/O for Samba on Linux
kernels that have the kernel AIO calls 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_linux module was written.
It uses the Linux kernel AIO interface instead of the internal Posix
AIO interface to allow read and write calls to be processed
asynchronously. A queue size of 128 events is used by default. To
change this limit set the "aio num events" parameter below.
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_linux
OPTIONS
aio_linux:aio num events = INTEGER
Set the maximum size of the event queue that is used to limit
outstanding IO requests.
By default this is set to 128.
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.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+-----------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------------+
|Availability | service/network/samba |
+---------------+-----------------------+
|Stability | Volatile |
+---------------+-----------------------+
NOTES
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from
https://download.samba.org/pub/samba/stable/samba-4.7.6.tar.gz
Further information about this software can be found on the open source
community website at http://www.samba.org/.
Samba 4.7 08/01/2018 VFS_AIO_LINUX(8)