Raw logical volume

[mudsucker]

If I have a raw logical volume for a database and the PP size is 4 MB and there are 1000 PPs in the logical volume. How much usable space in bytes can the database use? Is it 4,294,967,296 which is the number of bytes in 4GB or another number? How much overhead in AIX is there for a raw device?

 

[khalidaaa]

Have a look in here:

http://publib.boulder.ibm.com/infoc....howtos/doc/howto/HT_baseadmn_definerawlv.htm

Regards,
Khalid

 

[HelloNair]

1000 PPs can have only 4000 MB with a PP size of 4 MB. Please note that 4GB is 4096 MB not 4000 MB.
The conversion in bytes is correct. 4 GB is 4,294,967,296 bytes.

The space that can be used by database on a raw logical volume depends on your configuration and environment. By default AIX uses the first 512 bytes for storing the LVCB data. While configuring the database, most of the database application skips the first few blocks and the space usage depends on your block size and application. According to my knowldge Oracle keeps an offset of 4KB.

In AIX 5.3 you can eliminate the LVCB by using creating the Logical volume with -TO option. So this space can be use for application. However you need to have the volume group in Big Volume Group format to do so

 

[mudsucker]

Thanks.