Secondary Storage

1
Secondary Storage

• FREC135

2
Volatile
Non-Volatile
System Unit
Secondary Storage
RAM
Cache
Disk
Cache
CPU
3
Terms

• Media physical material
• Capacity How much a medium can hold
• Access Time Time to retrieve data

4
Disk Media
5
Floppy Disk

• 3.5
• 2HD
• 1.44 MB Capacity

6
Zip Disk

• 100, 200 or 750 MB Capacity
• Faster

7
Hard Disks

• Several Platters
• 250GB Capacity
• Very Fast
• 7,200 10,000 RPM
• Types
• Internal (IDE, SATA, SCSI)
• Removable
• External (Firewire, USB II, SCSI)

http//en.wikipedia.org/upload/c/ca/Hard-drive-all
sorts-1990s-l.jpg
8
Hard Disks
9
Defragmenting

• Files may spread all over disk
• Defragmenting puts pieces of files next to each
  other on disk so they can be read faster

10
RAID

• Redundant Array of Inexpensive Disks
• Can provide speed and/or protection
• RAID0 Striping 0 makes 2 disks into one.
  Faster to read/write.
• RAID1 Mirroring 1 second backup disk.
  Storage cost ½ disk space
• RAID3 Parity 3 Can replace a disk without
  losing data. Storage cost 1/3 or less disk space

11
RAID

• Used to only be used in servers / data centers
• Recently in high-end gaming machines 1
• Need a RAID Controller card for good performance.
  Typically expensive, but getting cheaper 2.

12
Optical Disks

• How Optical Disks are made 1
• How Optical Storage works 2

13
Optical Disks

• CD
• CD-ROM (Read Only)
• CD-R (Recordable)
• CD-RW (ReWritable)
• 650-700 MB

14
Optical Disks

• DVD
• DVD-Rom (Read Only)
• DVD-RAM (Random Access)
• DVD-R, DVDR (Recordable)
• DVD-RW, DVDRW (ReWritable)
• 2.4 to 17 GB
• Blu-Ray soon. 27-50GB

15
Optical Disks

• Rotation speeds are about as fast as possible
• 52x CD ? 30,000 RPM
• Faster could be dangerous (if not already)
  12
• To transfer data faster, need to make the disks
  denser

16
Newer Media

• Solid State (SmartMedia, MMC, FlashDrive, etc.)
• Network Storage(http//www.freedrive.com, NAS)
• Paper Disks - http//news.bbc.co.uk/2/hi/technolog
  y/3639585.stm
• Mini Hard Drives - http//news.bbc.co.uk/2/hi/tech
  nology/3381997.stm