3.4.0 Matrix Server Administration Guide

Chapter 7: Configure PSFS Filesystems 76

Disk Quotas

Disk quotas are enabled or disabled at the filesystem level. When quotas

are enabled, the filesystem performs quota accounting to track the disk

use of each user having an assigned disk quota.

When you create a filesystem and enable quotas, you can also set options

including the default hard and soft limits for users on the filesystem. A

hard limit specifies the maximum amount of disk space in the filesystem

that can be used by files owned by the user. A soft limit is typically set

below the hard limit and triggers a warning when it is reached.

If you choose to enforce hard limits, when a file owner reaches the hard

limit, the filesystem will not allow the owner to create files or increase the

size of an existing file; any attempts to allocate more space will fail. The

file owner will need to remove files or reduce their size until the disk

usage falls below the hard limit.

Crash Recovery

When a server using a PSFS filesystem either crashes or stops

communicating with the matrix, another server in the matrix will replay

the filesystem journal to complete any transactions that were in progress

at the time of the crash. Users on the remaining servers will notice a slight

delay while the journal is replayed. Typically the recovery procedure

takes only a few seconds. The recovery process restores only the

structural metadata information. Any regular file data in the blocks that

were in use when the crash occurred may be corrupted or lost.

The server that crashed or lost communication with the matrix will not be

able to access the filesystem until it is rebooted.

Create a Filesystem

A PSFS filesystem can be created on a basic volume (a psd device) or a

dynamic volume (a psv device). You can create a filesystem from one

server in the matrix using either the PolyServe Management Console or

the command line. The filesystem can then be mounted on all servers in

the matrix that can access it via the SAN.

NOTE: The minimum size for a PSFS filesystem is 64 MB.