ldapv3.pdf 7947KB Apr 17 2013 11:30:42 AM - mirror omadata

Journalized Filesystems
Journalized Filesystems
By default slapd performs a fsync() call after every write operation, this
commits data from memory to disk in order to ensure data base integrity.
Performing fsync()s in this manner result in very ineffecient I/O
utilization.
This behaviour can be disabled via the dbnosync configuration
directive, but this is not recommended as you sacrifice database
integrity for your increase in performance.
Using data journalling permits the operating system to return
completion of fsync() calls as soon as the journal is updated. Since
the journal is written linearly it avoids elevator related performance
problems and avoids latency resulting from excessive head motion.
Data journalling can be enabled on ext3 using the data=journal
mount option.
Data journalling requires a significantly larger journal than does
meta-data only journalling.
Journal size and position can be modified via the tune2fs
utility.