Hello,

Would You like to explain me how jbase journal works ?
The jbase manual says :

When journaling is running the basic order of operations for updates is as 
follows: 
 
• The database item is updated in memory 

*• The transaction log is updated in memory*. 

• The transaction log is flushed every 10 seconds by default. However this 
time period can be configured via an option on the administration command, 
jlogadmin. It is also possible to configure an independent process to 
execute the jlogsync command, to ensure the transaction log is continuously 
flushed from memory at the specified interval, thus alleviating the flush 
procedure from all of the update processes. 

• The database updates are flushed to disk by the operating system. 

• The database update to disk and the log update to disk can be forced to 
be an atomic operation. 
 There is a feature which specifies the number of seconds between each 
synchronization of the log set with the disk  - jlogadmin -s nnn ; All 
memory used by the log set is force flushed to disk. Should the system 
crash, the maximum amount of possible data loss is limited to the updates 
which occurred since the last log set synchronization. By default it is 10 
seconds. What will be if I change this to f.e. 10.000 seconds ? - does that 
mean that I can lose informations from 10.000 seconds if my system will 
crash ?
In my opinion it's not true because I can observe modify time of logset 
files during a test and they are constantly updated - not in every 10 or 
10.000 seconds 
So what is responsible for logsets synchronization ?

Piotr
 

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