Device and Filesystem Management

CSCI N321 – System and Network Administration

Copyright © 2000, 2012 by Scott Orr and the Trustees of Indiana University

Section Overview

Devices and Files

Drives and Partitions

Filesystem Management

Network Filesystems

References

CQU 85321 System Administration Course

TextbookChapter 11

Lectures2002 #10

Kinds of DevicesPhysical Devices Actual hardware Examples

Hard Drives, CDROMs, Floppy Network cards and modems

Logical Devices Pseudo devices Examples

Virtual Terminals Network Ports

Interrupt Handling

UserUser

SupervisorSupervisor

SystemSystemCallCall

Interrupt Vector 0Interrupt Vector 0

Interrupt Vector Interrupt Vector n-n-11Interrupt Vector Interrupt Vector nn

InterruptInterruptHandler Handler nn

Interrupt vector tableInterrupt vector table

MemoryMemory

Trap Trap nn

Device Drivers and Files

Device drivers Software to control hardware Compiled into the kernel Dynamically loaded module

Device files Located in /dev Provide application access to device Driver must also be present to use

Making Device Files

mknod filename type major minor

filename: Name of the device fileType “c” – Character Device “b” – Block Device

Major Number: Type of device driverMinor Number: Instance (which one)/dev/MAKEDEV: Creation program

Disk Geometry

TracksTracksSectorsSectors

Read/write HeadsRead/write Heads

CylindersCylinders

PartitionsPartitions

PlattersPlatters

Common Disk Types

SCSI Many cable types

SATA (IDE Family)SASFibre Channel High Bandwidth

Solid State Devices (SSD)Universal Serial Bus (USB) Removable Media

UNIX FilesystemsDefines how data is stored on drivesMultiple types of filesystems supportedBoot Block (1st block) Stores the bootstrap loader program

Superblock (2nd block) Copies scattered throughout the partition Stores information about the partition

Partition Size Type of File system Block Size Size & Location of inode tables Free Block list

Filesystems and Partitions

/ (root)

bin varusretchome

scott bobalice bin sbin local lib

man lib srcsharebin

SuperSuperBlockBlock

GroupGroupDescriptorsDescriptors

Ext2/3/4 File Systems

BootBootBlockBlock Block GroupBlock Group Block GroupBlock Group Block GroupBlock Group

DataDataBitmapBitmap

InodeInodeBitmapBitmap

InodeInodeTablesTables

DataDataBlocksBlocks

NTFS File System

BootBootBlockBlock

Master FileMaster FileTable (MFT)Table (MFT)

SystemSystemFilesFiles File AreaFile Area

StandardStandardInformationInformation

File/DirFile/DirNameName

SecuritySecurityDescriptorDescriptor

Data orData orIndexIndex

Source: http://technet.microsoft.com/en-us/library/cc750198.aspxSource: http://technet.microsoft.com/en-us/library/cc750198.aspx

Why Partition?

Not enough space on one diskSeparation of data Read-only areas Spool areas and free space OS upgrades

BackupsPerformance

Virtual File SystemUser ProcessUser Process

Device DriverDevice Driver

NTFSNTFSISO9660ISO9660Ext3Ext3

System call InterfaceSystem call Interface

VFSVFS

Buffer CacheBuffer Cache

KernelKernel

Managing FilesystemsCreating a new filesystem Similar to DOS format mkfs – creates a filesystem (many aliases)

mount – mount a partition Mount point must exist (directory) /etc/fstab

umount – Unmount a partitionfsck Check/fix filesystem errors Journaling filesystems

Quotas?

RAID StorageRedundant Array of Independent (Inexpensive) DrivesLevel 0 – Data Blocks spread across 2 or more drives (striping). No fault toleranceLevel 1 – Each disk copied (mirrored) to another diskLevel 0+1 – Each drive with striped data is mirroredLevel 5 – Data and fault tolerance (parity) striped across disksLevel 6 – Same as level 5 but with 2 parity disks

RAID 0

Usable Storage? All

Performance? Read and Write

Improvement

No Fault Tolerance

Source: http://www.prepressure.com/library/technology/raidSource: http://www.prepressure.com/library/technology/raid

RAID 1

Usable Storage? ½ available

Performance Improvement Read

Fault Tolerant

Source: http://www.prepressure.com/library/technology/raidSource: http://www.prepressure.com/library/technology/raid

Raid 10

Storage Usage? ½ Available

Performance Read and Write

Fault TolerantRAID 0+1

Source: http://www.prepressure.com/library/technology/raidSource: http://www.prepressure.com/library/technology/raid

RAID 5

Need at least 3 DisksUsable Storage N – 1 (Disks)

Performance Improvement Read

Hot Spare(s)

Source: http://www.prepressure.com/library/technology/raidSource: http://www.prepressure.com/library/technology/raid

RAID 6

Need 4+ DisksUsable Storage: N -2 (Disks)Performance Improvement: ReadFault TolerantHot spare(s)

Source: http://en.wikipedia.org/wiki/Standard_RAID_levelsSource: http://en.wikipedia.org/wiki/Standard_RAID_levels

Logical Volume Management

Physical VolumePhysical Volume20GB20GB

Physical VolumePhysical Volume36GB36GB

Physical VolumePhysical Volume34GB34GB

/boot/boot2GB2GBext3ext3

Logical Volume GroupLogical Volume Group90GB90GB

Logical VolumeLogical Volume/home/home50GB50GB

Logical VolumeLogical Volume//

25GB25GB

Free SpaceFree Space15GB15GB

Network Filesystems

Filesystems shared via NFSClient-side: similar to local mountServer – exports shared filesystems mountd and nfsd /etc/exports and exportfs Access permissions should be selective

showmount –eCIFS – Microsoft filesystem sharing Samba – CIFS support for Linux/MAC

Printer Connections

Local Parallel USB

Remote/SharedNetwork

Printing Languages

PCL (Hewlett Packard)Postscript (Adobe)PDF (Adobe)XHTML

CUPS

Client/Server Applicationcupsd – CUPS Server cupsd.conf printers.conf classes.conf

Web Administration – Port 631

Printer Configuration

Printer NameConnection info Local (LPT, Serial, etc.) Network (lpd, JetDirect/Socket, HTTP) Shared (SMB)

Device Driver or PPDs

Print Commands

Printing lpr –P<printer> mpage –P<printer>

Queue Status: lpq –P<printer>Status: lpstat –tConfiguratation: lpadmin cupsenable/cupsdisable accept/reject

Windows Printer Management

“Devices and Printers”Add Printer Wizard Name Connection (Local or Address/Port) Device Make and Model

Printer Sharing