Home » Infrastructure » Linux » What is raw device, raw file?
What is raw device, raw file? [message #497083] Thu, 03 March 2011 22:23 Go to next message
snowball
Messages: 229
Registered: April 2006
Location: China
Senior Member

Hi, guys
I heard of that some one use dd command for formating a raw file to store data.

After googling, I just know raw file is a unformated file generally.

Could someone kindly explain ?

Br,
Milo
Re: What is raw device, raw file? [message #497116 is a reply to message #497083] Fri, 04 March 2011 01:06 Go to previous messageGo to next message
Michel Cadot
Messages: 66808
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
This question bears no real connection with Oracle.
Please find a more appropriate forum.
The topic is locked.
If I'm wrong, please, PM me (or report this message to a moderator, explain why you think it should be unlocked and it might be done).

Regards
Michel
Re: What is raw device, raw file? [message #503070 is a reply to message #497116] Tue, 12 April 2011 11:47 Go to previous message
smiths
Messages: 1
Registered: May 2005
Junior Member
Hi

Raw File :

Windows supports raw files, similar to UNIX. Using raw files for database or log files can have a slight performance gain. Raw files are unformatted disk partitions that can be used as one large file. Raw files have the benefit of no file system overhead, because they are unformatted partitions. However, standard Windows commands do not support manipulating or backing up raw files. As a result, raw files are generally used only by very high-end installations and by Oracle Real Application Clusters, where they are required.

To Oracle Database, raw files are no different from other Oracle Database files. They are treated in the same way by Oracle Database as any other file and can be backed up and restored through Recovery Manager or OCOPY.



Raw Device :
A raw device is a portion of a physical disk that Oracle8i on Windows NT uses for its database files. Raw devices are not like regular file management systems. The information they store cannot be identified or accessed by users. The use of raw devices may improve disk I/O performance by 5% to 10% when compared with disk I/O to a partition with a file system on it.

A raw device is created when an extended partition is created and logical partitions are assigned to it without applying any formatting. The Windows NT Disk Administrator application allows you to create an extended partition on a physical drive.

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