10-26-2009
The write operations are almost certainly getting cached somewhere, most likely in the kernel page cache or the cache on the disk(s) themselves depending on your OS and hardware setup.
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LEARN ABOUT CENTOS
vfs_cacheprime
VFS_CACHEPRIME(8) System Administration tools VFS_CACHEPRIME(8)
NAME
vfs_cacheprime - prime the kernel file data cache
SYNOPSIS
vfs objects = cacheprime
DESCRIPTION
This VFS module is part of the samba(7) suite.
The vfs_cacheprime VFS module reads chunks of file data near the range requested by clients in order to make sure the data is present in
the kernel file data cache at the time when it is actually requested by clients.
The size of the disk read operations performed by vfs_cacheprime is determined by the cacheprime:rsize option. All disk read operations are
aligned on boundaries that are a multiple of this size. Each range of the file data is primed at most once during the time the client has
the file open.
This module is stackable.
OPTIONS
cacheprime:rsize = BYTES
The number of bytes with which to prime the kernel data cache.
The following suffixes may be applied to BYTES:
o K - BYTES is a number of kilobytes
o M - BYTES is a number of megabytes
o G - BYTES is a number of gigabytes
EXAMPLES
For a hypothetical disk array, it is necessary to ensure that all read operations are of size 1 megabyte (1048576 bytes), and aligned on 1
megabyte boundaries:
[hypothetical]
vfs objects = cacheprime
cacheprime:rsize = 1M
CAVEATS
cacheprime is not a substitute for a general-purpose readahead mechanism. It is intended for use only in very specific environments where
disk operations must be aligned and sized to known values (as much as that is possible).
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.
Samba 4.0 06/17/2014 VFS_CACHEPRIME(8)