3.4.0 Matrix Server Administration Guide

Chapter 17: SAN Maintenance 190

• Repeated I/O errors when the server tries to write to a PSFS journal.

The server then loses access to the affected filesystem. When the disk

experiencing the I/O errors is fixed, the server will automatically

regain access to the filesystem.

The PolyServe Management Console typically displays an alert message

when a server loses access to the SAN. (See Appendix B for more

information about these messages.)

Membership Partitions

Matrix Server uses a set of membership partitions to control access to the

SAN and to store the device naming database, which includes the global

device names for SAN disks imported into the matrix. Typically, the

membership partitions are created when you install Matrix Server.

When a membership partition is placed under Matrix Server control,

write access is disabled to prevent accidental corruption from other

applications.

The following commands can be useful in diagnosing or repairing

problems with the membership partitions:

•The mxsanlk command reports the status of the SAN ownership locks

used to control access to the SAN. These locks are stored on the

membership partitions.

•The mprepair command can be used to repair membership partitions.

Display the Status of SAN Ownership Locks

Matrix Server uses a set of disk-based data structures called SANlocks to

protect filesystem integrity. If a problem causes a matrix to split into two

or more network partitions, the SANlocks ensure that only one of the

resulting network partitions has access to the SAN.

Each SANlock is stored in a membership partition. Before a matrix can

begin accessing the SAN, it must first acquire a majority of the SANlocks.

The SANlocks are acquired in order.

mxsanlk displays the status of the SANlock stored in each membership

partition. It can be used to determine whether any of the membership