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Full Discussion: Synchronising cache and file
Top Forums Programming Synchronising cache and file Post 302997178 by sundaresh on Tuesday 9th of May 2017 05:36:38 AM
Old 05-09-2017
Synchronising cache and file

I am reading and caching some of the blocks of a large data file into program
virtual memory, for processing. My question is how do I synchronise this
cache with the file, for instance, if a block in the cache is updated or written to,
that block has to be updated in the underlying file. If this process is delayed
or only partly completed, will not the file be inconsistent. This can happen
if there is a power failure. How is this problem handled by DBMS programs ?
I am programming in C. Any answers and references to good books or readily available reading material on this subject will be gratefully appreciated.
 

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dbc_max_pct(5)							     OBSOLETED							    dbc_max_pct(5)

NAME
dbc_max_pct, dbc_min_pct, bufcache_max_pct, bufpages, nbuf - OBSOLETED kernel tunable parameter DESCRIPTION
These tunables have been obsoleted and removed. Do not make any changes to these tunables, as they have no effect on the kernel. Use the file cache tunables and (see filecache_max(5)). In previous releases, the tunables and were used to set limits to the dynamic buffer cache, and the tunables and were used for tuning the buffer cache when a static cache was desired. This release of HP-UX offers improved file caching technology and improved physical memory control associated to caching file I/O data. The number of tunable parameters used to control file caching memory usage is reduced from five to two, and previous usability issues are addressed. Restrictions on Changing These tunables should not be modified. Attempting to tune any of the obsolete buffer cache tunables, or results in an error. Use the tunables and to set limits on the file cache. Note that, on a any given system, the optimum values of these two new tunables are not necessarily equivalent to the optimum values of the obsolete buffer cache tunable values in the older systems. You should first deter- mine if the new default values yield acceptable performance on your system, before attempting to change the values of the new file cache tunables. AUTHOR
and were developed by HP. SEE ALSO
filecache_max(5). Kernel Tunable Parameter dbc_max_pct(5)
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