From owner-freebsd-questions  Wed Sep 22  8:21:17 1999
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From: Alexander Maret <maret@atrada.de>
To: "'freebsd-questions@freebsd.org'" <freebsd-questions@freebsd.org>
Subject: softupdates: do I understand this correctly?
Date: Wed, 22 Sep 1999 17:21:31 +0200
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I've read the abstract about SoftUpdates but as 
my english is not that good I'm not sure if I 
understood everything correctly:

Here is my current view of this topic:

synchronous mode:
doing a write operation in this mode causes the
system to write all dependenies and then write the
data to disk. The system waits for every command
to be completed. Therefor this mode is slow but safe.

asynchronous mode:
the system starts every command (i.e. write dependencies,
write data) and doesn't wait for the command beeing 
completed. Because of data being cashed this mode is not
very safe.

softupdates mode:
the system cashes data and tracks dependencies to write 
cashed data (including dependencies) afterwards in one go 
(=delayed write). 

advantage of softupdates:
- in case of a crash it is more likely that every data is
already been written to disk because the system writes data
in one go and doesn't have to wait i.e. for a program output 
while there is an open file.


Can anybody confirm this or do I have a completly wrong
view of this topic. Please comment my thoughts.

Alex


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