Two-Minute Drill

Understanding Disk Architecture

q	A disk consists of multiple platters, each of them divided into concentric circles called tracks. A set of tracks, one from each platter, at an equal distance from the center, is called a cylinder.
q	A track is divided into sectors, and a sector has a typical capacity of 512 bytes. A file consists of blocks, and a block may occupy one or more sectors on the disk.
q	A physical device name represents the full path name for a device in the device information hierarchy; it is created when the device is connected for the first time to the system.
q	An instance name is an abbreviated name for a device that the kernel uses to refer to the device.
q	A logical device name is the name for a device that the system administrator uses in system commands.

Partitioning a Disk

q	Each disk slice can hold only one slice, and vice versa.
q	A slice cannot span multiple disks.
q	You cannot change the size of a slice after creating a file system on it without re-partitioning.
q	In a VTOC disk, slice 2 is reserved for referring to the entire disk, whereas in an EFI disk, you can use it to meet your needs.
q	The disks are partitioned by using the partition option from the menu provided by the format utility.

Listing and Reconfiguring Devices

q	You can use the prtconf and sysdef command to find out the device configuration information including the list of devices that can also be found with the demesg command.
q	The /etc/patb_to_inst file is maintained by the system and is used at the startup time. Do not remove it, and if you have to edit it, be careful in making changes.
q	The devfsadm command by default loads all the drivers, but it can also be used to configure only the newly added devices so that you don't have to reboot the system.

Mounting and Unmounting a File System

q	The mountall command is automatically executed when the system enters the multiuser mode, and it mounts all the file systems specified in the /etc/vfstab file.
q	The /etc/mnttab file is a read-only file and contains a table of all the file systems currently mounted on the local system.
q	You can mount an individual file system from the command line by using the mount command and unmount it by using the umount command.