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Full Discussion: How raw disks are read?
Top Forums UNIX for Advanced & Expert Users How raw disks are read? Post 302802765 by methyl on Saturday 4th of May 2013 06:13:54 PM
Old 05-04-2013
Point: With modern hardware a "raw disc" can be multiple physical discs which the Operating System sees as one physical disc.

Some research ideas:

Consider the case of a virgin disc. There are no filesystems unless your software creates a filesystem. You can write or read whatever you like within the physical dimensions of the disc.

The very basic filesystems follow the pattern of the original IBM tape format VOL1 HDR1.

For research purposes it is worth a look at CAFS (Content Addressable File Store). That's the way to use a raw disc! It's so much better than "Binary Tree", "Hash Random" or "Index Sequential" file systems when dealing with disorganised data.
 

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LEARN ABOUT DEBIAN

ql-dynamic-tgt-lun-disc

ql-dynamic-tgt-disc(8)					       System Administration					    ql-dynamic-tgt-disc(8)

NAME

       ql-dynamic-tgt-lun-disc - Scans for newly added LUNs.

SYNOPSIS

       ql-dynamic-tgt-lun-disc [OPTIONS]

DESCRIPTION

       Dynamic TGT-LUN Discovery Utility

       This  utility  scans  for  newly added LUNs. After adding new LUNs, you do not need to unload, then load the QLogic FC driver or reboot the
       system

       To begin scanning the LUNs issue following command:

	      # /usr/sbin/ql-dynamic-tgt-lun-disc

       -al,   --allow-lip
	      LIP is not issued by default, even if it is required for scanning new LUNs Setting this option, allows the utility to issue LIP.

       -cl, --current-luns
	      Displays LUNS currently present

       -e,  --extended-scan
	      Use this option as "-e | --extended-scan". to rescan LUNs. This will identify any change in attributes of existing LUNs. This option
	      can be used in combination of scan/refresh or max luns

       -h,  --help, ?
	      Prints this help message

       -i,  --interactive
	      Use this option to use the menu driven program

       -is,  --iscsi
	      Use this option to operate on ISCSI HBAs, this option can be used in combination of any other supported option.

       -m,  --max-lun
	      To set the maximum LUNs to be scanned

       -p,  --proc
	      Use PROC file system for LUN scanning

       -r,  --refresh
	      To refresh, that is remove LUNs that are lost use the options "-r|--refresh". This will remove the LUNs which no more exist.

       -s,  --scan [ -r|--refresh ]
	      The QLogic LUN scan utility re-scans all the devices connected to the QLogic HBA

SEE ALSO

       ql-lun-state-online(8), ql-hba-snapshot(8), ql-set-cmd-timeout(8)

Matthias Schmitz <;matthias@sigxcpu.org> 			     July 2009						    ql-dynamic-tgt-disc(8)
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