Re: raid 1 and df command

On Thursday 31 August 2006 17:04, ipyasaswi@xxxxxxxxx stood up and addressed
the masses in /comp.os.linux.misc/ as follows...:

I got a new server with four 80 GB disks. I create hardware raid 1
(mirroring) on first two disks. Then I created raid 1 (mirroring) on
second two disks. I installed Fedora 5 default install. After
installation from the command prompt, when I typed df -k I see a total
space of about 300 GB. How is that possible?
The OS should see only 160 GB right because the first disk is mirrored
to 2 disk and third disk is mirrored to fourth disk.
While booting up the the message does show two volume groups with 73 GB

Two groups of 73 GB sounds about right, because the Linux kernel counts in
binary fashion - i.e. using powers of two - while the disk manufacturers
provide the capacity in a decimal fashion, i.e. using powers of ten.
Therefore, a disk sold as having an 80 GB capacity could indeed turn out
about 73 GB - probably a bit more - as seen from within the operating
system environment.

On account of the 300 GB, that's possibly because your kernel allows the
physical components of a hardware RAID to be seen as individual disks.

Some RAID controllers and their drivers allow an operating system to look
beyond the RAID set-up, which allows for forensics and very low level
maintenance jobs even in hardware RAID set-ups.

It all depends on the controller and the driver module. ;-)

--
With kind regards,

*Aragorn*
(registered GNU/Linux user #223157)
.

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