1. Disk Volume Management CSS-1

2. Terms  Extent – any contiguous set of clusters  Partition – extent treated as a disk  Volume - partition formatted with a file system  Basic disk - basic volumes and logical drives  Dynamic disks CSS-2 © 2012 D. J. Foreman

3. WINDOWS CSS-3 © 2012 D. J. Foreman

4. Basic disk  Exists on single physical drive  Uses DOS partition tables ■ Simple volume (contiguous extents) ■ Primary partitions ■ Extended partitions ■ Logical drives ■ USB removable drives CSS-4 © 2012 D. J. Foreman

5. Dynamic disks (Windows)  Simple volume ≈ primary partition or logical drive  Only 1 user accessible partition  Not for bootable volumes  Up to 1000 volumes on a system  Rely on Logical Disk Manager (LDM) and Virtual Disk Service  Allows non-contiguous extents CSS-5 © 2012 D. J. Foreman

6. Dynamic disk volume types  Spanned volumes  Extended volumes  Striped volumes  Mirrored volumes  Raid-5 volumes CSS-6 © 2012 D. J. Foreman

7. Partitions  Master Boot Record (DOS style) for Windows ■ 2 choices ●4 primary partitions (maximum) ●3 Primary + 1 extended partition  Globally Unique ID style ■ Basic disk: Up to 128 primary partitions ■ Dynamic disk: 1 LDM partition (like MBR) CSS-7 © 2012 D. J. Foreman

8. GUID  Allows partitions > 2 terabytes  Added reliability ■ Replication & CRC for partition table CSS-8 © 2012 D. J. Foreman

9. MBR example (Basic disk) CSS-9 © 2012 D. J. Foreman 1st Ptable entry Master boot code 2 nd Ptable entry 3 rd Ptable entry 4 th Ptable entry Partition table 0x55AA MBR Primary Partition 1 C: Primary Partition 2 E: Primary Partition 3 F: Logical Drive G:: Logical Drive H:: Extended Partition Extended partition does NOT have to be last. Must be contiguous space.

10. Dynamic disk MBR  Similar to Basic MBR layout  No extended partitions  Only ONE Primary partition ■ Called the LDM partition  Hidden partition at end for LDM DB CSS-10 © 2012 D. J. Foreman

11. Dynamic disk  Contains: ●simple volumes ●spanned volumes ●striped volumes ●mirrored volumes* ●RAID-5 volumes* * Depends on O/S version CSS-11 © 2012 D. J. Foreman

12. Dynamic Storage Terms  Simple vol: space on 1 disk  Spanned vol: linked space on ≥ 1 disks ■ NOT fault tolerant ■ CANNOT be mirrored CSS-12 © 2012 D. J. Foreman

13. LINUX CSS-13 © 2012 D. J. Foreman

14. A truism  On a Unix system, everything is either a file or a process.  Directories are just files with names of other files  Devices are treated as files with special attributes  http://en.wikipedia.org/wiki/Comparis on_of_file_systems http://en.wikipedia.org/wiki/Comparis on_of_file_systems CSS-14 © 2012 D. J. Foreman

15. Partition management  Logical Volume Manager (kernel)  Loaders ■ LILO (LInux boot LOader) ■ GRUB (GRand Unified Boot loader)  Partitioning programs ■ fdisk ■ Gparted (Gnome partition editor) ■ KDE Partition Manager CSS-15 © 2012 D. J. Foreman

16. Layout (from Wikipedia) CSS-16 © 2012 D. J. Foreman PE=Physical Extent

17. Linux File Systems  Ext (1992)  Ext2 (1993)- pref for SD & USB  XFS (1994) – B-tree larger than its files  Ext3 (1999) – journal, slow, htree index, max filesystem size=32TB  Ext4 (2006) – max filesystem size=1 EB (1M TB) CSS-17 © 2012 D. J. Foreman

18. Htree indexing  Constant depth of 1 or 2 levels  Hashes filename  No rebalancing CSS-18 © 2012 D. J. Foreman