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<samba:parameter name="strict allocate"
context="S"
type="boolean"
xmlns:samba="http://www.samba.org/samba/DTD/samba-doc">
<description>
<para>This is a boolean that controls the handling of
disk space allocation in the server. When this is set to <constant>yes</constant>
the server will change from UNIX behaviour of not committing real
disk storage blocks when a file is extended to the Windows behaviour
of actually forcing the disk system to allocate real storage blocks
when a file is created or extended to be a given size. In UNIX
terminology this means that Samba will stop creating sparse files.</para>
<para>This option is really desgined for file systems that support
fast allocation of large numbers of blocks such as extent-based file systems.
On file systems that don't support extents (most notably ext3) this can
make Samba slower. When you work with large files over >100MB on file
systems without extents you may even run into problems with clients
running into timeouts.</para>
<para>When you have an extent based filesystem it's likely that we can make
use of unwritten extents which allows Samba to allocate even large amounts
of space very fast and you will not see any timeout problems caused by
strict allocate. With strict allocate in use you will also get much better
out of quota messages in case you use quotas. Another advantage of
activating this setting is that it will help to reduce file
fragmentation.</para>
<para>To give you an idea on which filesystems this setting might currently
be a good option for you: XFS, ext4, btrfs, ocfs2 on Linux and JFS2 on
AIX support unwritten extents. On Filesystems that do not support it,
preallocation is probably an expensive operation where you will see reduced
performance and risk to let clients run into timeouts when creating large
files. Examples are ext3, ZFS, HFS+ and most others, so be aware if you
activate this setting on those filesystems.</para>
</description>
<value type="default">no</value>
</samba:parameter>
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