HP-UX HB v13.00 Ch-14 - JFS

HP-UX Handbook – Rev 13.00 Page 14 (of 47)
Chapter 14 Journaled File System (JFS)
October 29, 2013
Support for databases
Databases are usually created on file systems to simplify backup, copying, and moving tasks and
are slower compared to databases on raw disks.
Using Quick I/O for Databases feature with VxFS lets systems retain the benefits of having a
database on a file system without sacrificing performance.
Veritas Quick I/O creates regular, pre-allocated files to use as character devices. Databases can
be created on the character devices to achieve the same performance as databases created on raw
disks. Treating regular VxFS files as raw devices has the following advantages for databases:
Commercial database servers such as Oracle Server can issue kernel supported asynchronous I/O
calls (through the asyncdsk or Posix AIO interface) on these pseudo devices but not on regular
files.
Cluster file systems
Veritas Storage Foundation Cluster File System (SFCFS) allows clustered severs to mount and
use a file system simultaneously as if all applications using the file system were running on the
same server. The Veritas Volume Manager cluster functionality (CVM) makes logical volumes
and raw device applications accessible through a cluster.
Beginning with SFCFS 5.0, SFCFS uses a symmetric architecture in which all nodes in the
cluster can simultaneously function as metadata severs. SFCFS still as some remnants of the old
master/slave or primary/secondary concept. The first server to mount each cluster file system
becomes its primary; all other nodes in the cluster become secondaries. Applications access the
user data in files directly from the server on which they are running. Each SFCFS node has its
own intent log. File system operations, such as allocating or deleting files, can originate from any
node in the cluster.
NOTE: Installing VxFS and enabling the cluster feature does not create a cluster file system
configuration. HP Serviceguard Storage Management environments require HP Serviceguard for
file system clustering.
To be a cluster mount, a file system must be mounted using the mount -o cluster option. File
systems mounted without the -o cluster option are termed local mounts.
Cross-platform data sharing
Cross-platform data sharing (CDS) allows data to be serially shared among heterogeneous
systems where each system has direct access to the physical devices that hold the data.
NOTE: This feature can be used only in conjunction with Veritas Volume Manager