3.1.2 Matrix Server Administration Guide

Chapter 7: Configure PSFS Filesystems 89

Filesystem Restrictions

The following restrictions apply to the PSFS filesystem:

• A PSFS filesystem cannot be used as the root or /boot filesystem.

• A server can mount another non-shared filesystem on a directory of a

PSFS filesystem; however, that filesystem will be local to the host. It

will not be mounted on other hosts in the matrix.

• PSFS filesystems cannot be mounted using the Linux loop device.

These filesystems can be accessed only as SCL-managed “psd” or

“psv” devices.

• The loopback driver cannot be used in conjunction with files located

on a PSFS filesystem.

• Swap files are not supported.

•Certain fcntl APIs for user-level applications are not supported. This

includes

F_GETLEASE, F_SETLEASE, F_NOTIFY, and mandatory locks.

• All options of the mmap system call are supported. However, when

using PROT_WRITE/MAP_SHARED mmaps, cross-server coherency

of the mapped regions is not guaranteed. All processes using writable

shared mmaps to share data must be on the same server.

•The

ETXTBSY mechanism is not supported. Processes will not be

prevented from writing to running executable files.

Matrix Server Database Option

Matrix Server Database Option provides a mount option that is

optimized for filesystems containing database data files. In practice, place

all database files that would otherwise need to be located in a shared raw

partition in this type of Matrix Server mount. Examples include Oracle

Clusterware (e.g., Oracle9i OCMS, Oracle10g CRS) files.

The mount option turns off filesystem buffering, allowing the database

files to be accessed directly for direct DMA to and from the application.

The mount option also turns off the filesystem’s file data coherency

control, allowing the database to manage the coherency of its own data

files. Matrix Server Database Option is available as a separately licensed

product.