| What is raw device, raw file? [message #497083] |
Thu, 03 March 2011 22:23  |
snowball
Messages: 229
Registered: April 2006
Location: China
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Senior Member |
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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
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| Re: What is raw device, raw file? [message #503070 is a reply to message #497116] |
Tue, 12 April 2011 11:47  |
smiths
Messages: 1
Registered: May 2005
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Junior Member |
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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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