5. File Systems, Formatting,and Fragmentation
Objectives:
- Define filing system, volumes, and partitions.
- Differentiate between the common file systems, and know which
ones are compatible with which systems.
- Describe formatting, and the differences
between high and low-level formatting.
- Define fragmantation, and methods to avoid or correct it.
Reading:
Chapter 5.3 - 5.4, Desktop Audio Technology - Rumsey
Filing Systems and Volume Partitions
Data Files and Filing Systems
- Files are stored on disks in data blocks. Most files require several
blocks of storage.
- File system - a method of cataloging where data is
stored on the drive.
- Defined by the operating system
- Determines whether files are accessible by the host system (i.e.
You can't open a Mac formatted HFS+ hard drive on a Windows XP computer without
special translation software to read the HFS+ formatted files)
Volumes
- Any data device that has been formatted, and is recognized
(mounted) by the computer
- Can be a unique physical device, or a partition of a given device
- Can be denoted as D:, E: drives on Windows, or just other drives/partitions
on mac as seen above.
Partitions
- A single drive can be divided into multiple distinct "logical" sections,
each able to be formatted as a separate volume
- Some computer systems will allow multiple types of systems on different partitions on the same drive
Various File Systems
- Proprietary systems used to be fairly common due to limitations of hard drive technology
- Standard drives were not fast enough for audio usage
- Custom systems resulted in faster access of data
- Expensive, non-standard, not interchangeable
- Now standard file systems are used
- Standard file systems have the advantage of being compatible across different computers
Microsoft File Systems
- Section at beginning of hard drive (File Allocation Table for FAT, Master File Table (MFT) for NTFS) is designated for information
about the rest of the drive
- Acts as a "table of contents" defining where data blocks are that hold
a file
Fat (or Fat16)
- Introduced with MS-DOS back in 1981
- Hasn’t been used for an OS since Windows 95
- Still used on thumb drives, floppies
- Limited to 2 GB size due to fixed-cluster structure (clusters must increase in size for bigger drives,
32KB cluster size at 2 GB)
Fat32
- Introduced in Windows 95 Service Pack 2 Update
- Same as Fat16 only with more available clusters
- File size limited to 4GB
NTFS
- Introduced for Windows NT (current Windows XP, Vista, etc is NT-based)
- Allows for quotas, encryption, compression, and increased security
- Many FAT-based platforms can’t read NTFS
- Faster than FAT
- File size limited only by size of partition
WinFS
- New file system under development; eliminates file hierarchy
- NTFS is recommended for audio workstations
Macintosh File Systems
Macintosh File System (MFS)
- Introduced in 1984, replaced in 1985
- Doesn’t support file hierarchy
- obsolete
Hierarchical File System (HFS)
- Introduced in 1985
- Files can have multiple forks (resource fork and data fork)
- Similar in limitations to Fat16
- obsolete
HFS+- Also called MacOS Extended
- Current file system for Macs
- De-fragments files under 20 MB “on-the-fly”
- More efficient use of space
- HFS+ is recommended for audio workstations
- Journaling
- Good for disaster recovery
- Can be slower - possible problem for audio usage
- Digidesign used to discourage it, now uses it...
File System Compatibility
Reading with Windows XP
- Doesn’t read HFS or HFS+
- a special external program will allow access to HFS disks (ex. Mac Drive)
Reading with OS X
- NTFS: read-only (or use a program like NTFS
- FAT16 and FAT32: full access
- WinFS: who knows?
- Boot Camp: run windows on your Mac Boot Camp
Formatting
- Process in which a drive is divided into tracks and sectors
- Sets up directory and file system
Formatting Methods
Low Level - Erase entire hard drive and format according
to file system above
- A more accurate name is “zero-fill”
- Writes ‘zeros’ to every sector on the hard drive
- True “low level” formatting happens at the factory
for all modern hard disks
- Outlines positions of sectors and tracks on the disk
- Desktop Audio Technology Def: “When a disk is
formatted at a low level the sector
headers are written and the bad blocks mapped out.
- Process can be lengthy unless you have a fast computer
- Zero-fill utilities are free and are manufacturer-specific
High Level - Primarly deletes table of contents
so the drive *appears* empty to the Operating System
- Rumsey: Disk is “subdivided into a number of ‘partitions’” (see
p. 152 for info. and diagram)
- Rumsey: “Each volume then has a directory created, which is an area of storage set aside to contain
information about the contents of the disk. The directory indicates the locations of the files, their sizes,
and various other vital statistics.”
- Typically does not actually erase data, just erases header info. and directory tree
Volumes and Partitions
- A volume is a formatted device that can contain data (can be a hard drive,
DVD, CD Rom, Flash Drive, etc)
- The formatting process defines disk volumes
- Partitions are set up during the formatting process
- One drive can contain multiple partitions - they appear as separate "drives" to
the OS - show as separate volumes
- Useful for keeping audio files separate from system files if you only
have one internal drive to work with
Cluster Size
- The smallest block of data that can be written to the hard disk
- Number of clusters can be defined by the total number of disk addresses
available
- Use 4KB cluster size for OS partitions
- Use biggest cluster size (currently 64KB) for audio partitions
Formatting and Operating Systems
Windows Formatting
- Windows XP and 2000 includes “Disk Management” utility for formatting & partitioning
- More powerful programs exist (ex. Partition Magic)
Macintosh Formatting
- Mac OS includes “Disk Utility” for formatting & partitioning
- 3rd party programs also exist for Mac - "Disk Warrior"
"Norton"
- UNIX command-line utilities available (if you know UNIX...)
For Audio
- Helpful to keep OS and audio files on separate hard disks (so the system
doesn't scatter audio file pieces in with System file pieces)
- A separate partition will not give the same result as a separate drive (contrary
to popular belief), but is superior to just putting all files on
same drive if you have only one internal.
- If possible, make clusters as large as possible for audio drives or volumes
Fragmentation
- Rumsey’s def: “When an erasable volume like a hard disk has been used for some time there will be a lot of files on the disk, and probably a lot of small spaces where old files have been erased.”
- Reduces disk performance by increasing access time for files
- Fragmentation seriously affects the performance of audio workstations
How De-fragmentation Works
- De-fragmentation program “...juggles the blocks of files between disk areas and temporary RAM.” (Rumsey)
- Re-arranges data blocks, assembling files into contiguous blocks on disk
- Power failure during de-fragmentation can be catastrophic
Windows Fragmentation
- NTFS and FAT file systems both fragment over time; de-fragmentation utility must be periodically run
- “Disk Management” can be used for de-fragmentation of drives
Disk Management
- More powerful programs exist
- Executive Software’s “Diskeeper” constantly de-fragments while running as a low priority, background application
- Doesn’t affect performance; eliminates need for manual de-fragmentation
Diskeeper
- File
Table and Paging File can become fragmented; “Disk Management” won’t fix
this, but Diskeeper will using boot-defrag
Macintosh Fragmentation
- HFS+ includes “on-the-fly” de-fragmentation
- only works for files under 20 MB
- Ineffective if drive is over 75% full
- On audio workstations, manual de-fragmentation should still be performed periodically
- 3rd party utilities must be used; OS X doesn’t include a utility
- General web sites: search for “optimizing XP for audio” or “optimizing OSX
for audio” on the web
