<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-4ADDC0D4-F784-5023-BD82-F6223C8DC79E" xml:lang="en"><title>File

Systems Overview</title><shortdesc>Provides several common file system implementation. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-B12E9720-673F-57FB-AF27-B0C2F5D1DDDA"><title>Purpose</title> <p>Provides

file system implementations —<i>file server fsy plug-ins</i> — for devices

that are reasonably expected to be used on a Symbian platform device. The

file systems implement a storage and access format most appropriate to the

media. Please see a file system's guide for its specific purpose. </p> </section>

<section id="GUID-0AB0FA58-037F-542D-8BBB-D1E9661202FB"><title>Architecture</title> <p>The

File Systems collection provides several kinds of file system implementations.

File system binaries are built as <xref href="GUID-BB9760B4-4F3F-5326-81FB-B644C82F0E65.dita">FSY</xref> plugins

that are loaded (added and mounted) by the file server; either at startup

or as required such as when a device is physically attached to the phone (inserting

a memory card into the card slot). </p> <p>The file server uses these implementations

to access data on different media. </p> </section>

<section id="GUID-6CACBD32-7E8A-5266-96D0-C2C2D82BC866"><title>Description</title> <p>The

File Systems collection consists of a series of file server plugins, one for

each file system. The various systems are loaded into a file server instance.

Different devices use different file systems based on the characteristics

of the storage medium. </p> <p>The following table lists several file systems

and the different media that use them. </p> <p>The ROM file system is implemented

as part of the file server component. The other files systems are implemented

as separate file server plugins, which may be loaded using ESTART or as part

of a mounting operation. </p> <p>All file system plugins files have .fsy extensions. </p> </section>

<section id="GUID-952FDE22-385B-5048-A546-B57A79F90B48"><title>File System

Summary</title> <p>The following file system plug-ins are provided: </p> <ul>

<li id="GUID-5E4EAEEA-CA8B-5AE2-9D52-751CF3F921F0"><p><xref href="GUID-596E9D8B-7E75-5644-B4DC-6D657BE00A8B.dita">Composite

File System</xref> (<filepath>ecomp.fsy</filepath>): The Composite File System

for NAND flash devices presents a single drive Z: to the File Server that

layers thinly over both the core ROM and the ROFS file systems. It redirects

File Server requests to the core ROM or ROFS as required. See <xref href="GUID-775B5858-4358-5195-B580-7C16AE4981C3.dita">Flash

Translation Layer Technology</xref> for more information on why this is required. </p> <p>This

unifies the file systems for flash devices (ROM, ROFS and FAT file systems)

into a common file system that is used with drive <filepath>Z:</filepath>.

The file server will direct requests to the required file system as required. </p> </li>

<li id="GUID-82C41045-11E9-5FC9-AE1E-7626CE45EA61"><p><xref href="GUID-CDB35952-5EE3-5643-BA0A-341FE0FF1A02.dita">FAT

File System</xref> (<filepath>efat.fsy</filepath> or <filepath>elocal.fsy</filepath> when

built for an emulator target.) : The FAT File System implements a file system

that supports the VFAT standard. This is used for user data storage on NAND

Flash, internal RAM drives, and removable media. </p> <p>This is the file

system that was originally used by IBM PCs and is an industry standard for

file systems. It is supported by all operating systems that execute on PCs.

Symbian platform FAT only supports FAT12 and FAT16 types. </p> </li>

<li id="GUID-35A95C58-10C0-5503-A898-CB11AF121A77"><p><xref href="GUID-0988F387-5F26-512E-BDA4-D5800EEC2A77.dita">FAT32

File System</xref> (<filepath>efat32.fsy</filepath>): The FAT32 File System

implements the enhanced version of the FAT file system standard that includes

FAT32 support. </p> <p>The FAT32 file system is an update of the industry

standard FAT file system. The Symbian platform FAT32 file system supports

the FAT12, FAT16 and FAT32 file systems. </p> </li>

<li id="GUID-E48530A9-A7BE-5EB1-B2F4-70779963B898"><p><xref href="GUID-15DD2080-83D6-5DE0-8B75-D4A5934C8C91.dita">ISO9660

File System</xref> (<filepath>iso9660.fsy</filepath>): The ISO9660 File System

implements a ISO9660 file system, that reads CDROM and DVD-ROM. This is only

for the internal X86 port. </p> <p>The ISO9660 is an internationally agreed

standard for the file system used by CD-ROM and DVD-ROM media. </p> <p> <note> ISO9660

is for Symbian internal use only. </note> </p> </li>

<li id="GUID-19C89E46-95EC-5F0D-AF66-ADB94A2ED408"><p><xref href="GUID-6FD18A95-2530-565C-8C92-E893649F2E59.dita">LFFS

File System</xref> (<filepath>elffs.fsy</filepath>): The LFFS File System

provides data storage on NOR type flash memory, and is portable to a wide

range of Flash devices. </p> <p>LFFS is designed specifically to be used with

NOR flash and has the ability to protect itself against power loss. </p> </li>

<li id="GUID-9A1088B0-2928-5F1E-A73A-FE40254BB987"><p><xref href="GUID-57C0B4C9-255A-50CD-8E99-DD1A754060C0.dita">NTFS

File System</xref> (<filepath>ntfs.fsy</filepath>): The NTFS File System provides

read-only support for the NTFS file system standards. This is only for the

internal X86 port. </p> <p>This is the file system for Windows NT, Windows

2000, Windows-XP, Windows Server 2003, Windows Server 2008 and Windows Vista. </p> <p> <note> NTFS

is for Symbian internal use only. </note> </p> </li>

<li id="GUID-776918FD-4408-50D6-BEB2-9B1D991C1E97"><p><xref href="GUID-466628A1-80BB-57E7-8315-CD9E0A95CDC3.dita">ROFS

File System</xref> (<filepath>erofs.fsy</filepath>): The Read-only File System

(ROFS) supports a ROM-structured local file system that can be located on

NAND flash, or other media, where executables are not executed in place (non-XIP). </p> <p>ROFS

stands for Read Only File System and is used for accessing code storage on

media that cannot be executed in that media (otherwise known as non-XIP storage),

for example NAND flash. </p> </li>

<li id="GUID-2E0072DF-6234-5D61-BB44-0F6DE6D062CF"><p><xref href="GUID-EB6CA066-B567-5542-9D41-183B27A70B82.dita">ROM

File System</xref> (No FSY, ROM is the default file system build defined by <filepath>f32.iby</filepath>):

The ROM file system is used to access the "core ROM image": this contains

files that are copied from NAND Flash storage into RAM on boot. </p> <p>This

is the file system that is used when the phone boots up. </p> </li>

<li id="GUID-FC28E385-C8D1-5E90-B075-B8FA09FA09F5"><p><xref href="GUID-61BAA598-4D13-5859-8751-DA949744E27F.dita">USB

Mass Storage File System</xref> (<filepath>msfs.fsy</filepath> and possibly <filepath>msfs_db.fsy</filepath>,

depending on configuration): The USB Mass Storage File System is provided

to support a licensee-provided USB mass storage application, which allows

a desktop host computer access to a FAT-formatted drive on the phone. </p> <p>The <xref href="GUID-F3C8EB83-EBB3-5347-89B0-9A86D1864D12.dita">USB Mass Storage Server</xref> is

used when a USB memory device is connected directly to the device executing

Symbian platform. </p> <p>The <xref href="GUID-FA0A6825-88A8-549A-B360-E7D74EE79CF1.dita#GUID-FA0A6825-88A8-549A-B360-E7D74EE79CF1/GUID-BD5162E2-0D9C-5756-9804-556595330043">USB

Mass Storage File System</xref> is used when the media on the device is accessed

by an external device i.e. a PC when it is in "USB mass storage" mode. </p> </li>

</ul> </section>

<section id="GUID-2C14C280-9442-462A-BE5A-8C49A96FB8E4"><title>Using File

System Plug-ins</title> <p>The file systems are used to allow kernel access

to data on a media storage device such as Flash, MMC cards, SD cards, etc.

A file systems FSY plug-in must be added to the file server and mounted before

the kernel is granted access. </p> <p>Accessing a file system specific device

requires: </p> <ul>

<li id="GUID-5E8C4326-5A6F-51D7-9C84-8AF5F6BC36AF"><p>Adding a file system

to the file server using <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-51353BE2-9133-39F5-83F3-A5DB88D858CA"><apiname>RFs::AddFileSystem()</apiname></xref>  </p> </li>

<li id="GUID-DBC20D4D-D358-5668-B9D8-BDF68A441A7E"><p>Mounting the file system

using <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-0754C075-92B6-37B3-8959-61D8D65DB491"><apiname>RFs::MountFileSystem()</apiname></xref>  </p> </li>

</ul> <p>The file server handles all requests to access a mounted file system. </p> </section>

</conbody><related-links>

<link href="GUID-9E92EE30-F2E2-5F28-BB2A-391C09EC69D2.dita"><linktext>Using ECom</linktext>

</link>

<link href="GUID-F3BD37EC-0CCB-5859-908F-215E22C9FC20.dita#GUID-F3BD37EC-0CCB-5859-908F-215E22C9FC20/GUID-143780ED-4A23-5E72-A923-F605172EC8B5">

<linktext>File Server</linktext></link>