You specify the intent log size when creating a file system by using the
-o logsize option. With the Version 6 or 7 disk layout, you can dynamically increase or decrease the intent log size using the
log option of the
fsadm command. The
mkfs utility uses a default intent log size of 16 megabytes for disk layout Versions 4, 5, and 6. 64 megabytes is the default for Version 7. The default size is sufficient for most workloads. If the system is used as an NFS server or for intensive synchronous write workloads, performance may be improved using a larger log size. Version 7 is the default disk layout for VxFS 5.0.
With larger intent log sizes, recovery time is proportionately longer and the file system may consume more system resources (such as memory) during normal operation.
There are several system performance benchmark suites for which VxFS performs better with larger log sizes. As with block sizes, the best way to pick the log size is to try representative system loads against various sizes and pick the fastest.