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AmigaOS 4.0 - About OS4 - Commands

FS_SET_FLUSH_STRATEGY AmigaDOS
Purpose: To set the buffer strategy for the new file system API.
Format: FS_SET_FLUSH_STRATEGY <file system volume name> <strategy>
Template: DEVICE/A, STRATEGY/A
Path: C:FS_SET_FLUSH_STRATEGY
Whenever changes are made to the contents of a file system, the file system data structures may need to be updated. The updating process can involve changing several disk data blocks. If this process is interrupted, the data on the disk may no longer be consistent and require repairs. This reimplementation of the Fast File System tries hard not to leave the disk's data structures in an inconsistent state when changes are made. Unfortunately, for this goal to be reached, the data block manipulations have to be carried out in a certain order, and the changes need to be written back to disk at once. This takes time and has a negative impact on write performance.

If you are certain that you can do without this elaborate and slow data management scheme, you can change the file system's data flushing strategy. The default is "strict", which means that for each change made, the respective data block changes are immediately written back ("flushed") to disk. The alternative is the "relaxed" strategy, which will delay writing back block changes until either no disk activity has taken place in a while or further block changes are making it necessary to write older modified blocks back to disk. The relaxed strategy is generally faster, but also generally less reliable than the strict one.

The FS_SET_FLUSH_STRATEGY command can be used to change the flush strategy for the specified <file system volume name> as follows:

  • specifying 0 as the strategy parameter chooses the "strict" flushing strategy
  • specifying 1 as the strategy parameter chooses the "relaxed" flushing strategy
Example: 3.OS4:> FS_SET_FLUSH_STRATEGY SYS: 0
'SYS:' flush strategy = strict (was strict).
Reaffirms that the flushing strategy for the SYS: volume was 'strict'.


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Disclaimer: Amiga Auckland have prepared the above Information for the use of its members based on our experiences and as such is subject to revision at any time. Amiga Auckland cannot guarantee any of the Information and cannot be held accountable for any issues that may result from using it.


Copyright 2006 Amiga Auckland Inc. All rights reserved.
Revised: December 24, 2006.