What is the big difference between /dev/dsk and /dev/rdsk ?

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shyam gopal

  • Mar 23rd, 2006

/dev/dsk contains the logical device names used for mounting and unmounting filesystems

/dev/rdsk contains the raw device name that is used for creating file systems

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  • Mar 26th, 2006

Hi,Thank you for your good responce,If possible can you please explain the scenarios. when we are using /dev/dsk and /dev/rdsk. Thanks again.

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  • Apr 18th, 2006

In Solaris whenever you create a new slice using format command a raw physical slice or a Raw Device will be created which is addressed as /dev/rdsk/c#d#s# where # is the number for slice.

After formatting it with newfs command the slice will be addressed as /dev/dsk/c#d#s# which can now be used for mounting.

eg.   newfs /dev/rdsk/c0d0s4

       mkdir /oracle

       mount /dev/dsk/c0d0s4 /oracle

After mounting /dev/dsk/c#d#s# is called as Block Device

/dev actually contains logical device names which are links (Shortcuts in windows terminology) to actual physical devices in /devices directory.

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  • Jul 11th, 2006

Basically raw devices till of before creation of filesystems

Block devices are user after creation of file systems.

NB: this is just a thumb rule

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  • May 15th, 2008

Logical device:-->used by user. all logiacl device name are kept in /dev dir.logical name contain the controller number,target number,disk number and slice number.

/dev/dsk -->block disk device
/dev/rdsk-->character disk device

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  • Oct 8th, 2009

When you want to create a ufs on a slice you make #newfs /dev/rdsk/c#t#d#s#
when you want to mount a slice you can use # mount /dev/dsk/c#t#d#s#

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  • Jan 14th, 2012

I hope I understood this way:

raw disk device /dev/rdsk is using for system management/administration
block disk device /dev/dsk is using for I/O operations

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  • Apr 25th, 2012

/dev/dsk-block device /dev/rdsk -raw device

In /dev/rdsk if the data which is written did not used full 512bytes of a sector then for the next time we cannot use the left space.

where as /dev/dsk maintains a buffer memory from where the data is copied to disk so there is no loss of space.

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Jamal Daken

  • Mar 21st, 2013

Raw device deals with sectors the smallest units in disks which is 512 Bytes

Block device deals with blocks which are 8 K Bytes each in Solaris.

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