scsi raid geometry high-point rocketraid 1640

[Jerry McAllister]

On Mon, Apr 30, 2007 at 09:54:04AM +0200, Klaus Friis Østergaard wrote:

> 2007/4/30, Jerry McAllister <jerrymc at msu.edu>:
> >
> >
> >> Hi,
> >>
> >> I have a raidcontroller high-point 1640 with 4 disks of 400 GB in a raid
> >5
> >> array given me 1200 GB. The bios utility of the controller zero build
> >the
> >> array with 64 kb
> >>
> >> FDISK says that the geometry is 145923/255/63 and it is incorrect. Then
> >it
> >> says that for scsi it is the translation mode the raid controller is
> >using.
> >
> >Usually you want to accept what fdisk does.  Just make the slices
> >that you want.   Geometry is virtual on these systems.
> >
> >>
> >> How do I find this?
> >>
> >> If I continue with the defaults I only get 1144654 MB like missing 100
> >GB.
> >
> >Well, I would expect you to get something less than 1,490 GB just from
> >the difference between the manufacturer use of GB (1,000,000,000 Bytes)
> >and the way the OS uses GB (1,073,741,824 Bytes).
> 
> 
> That is the missing link, the raid controller says 1200 GB if recalculated,
> using 1.073741824 it gives  1,117.59  GB  multiplied by 1024 it gives
> 1144409 MB which is what FDISK gives default.

Wow.   Don't tell me I got one  (out of how many?).    
I shall celebrate.

////jerry


> 
> I don't know how much the raidcontroller eats up to manage
> >the raid.  Raid 5 takes a piece for its redundancy/error
> >correction.  A raid 5 would eat at least 20% and maybe up to 30% if it
> >is rather inefficient.
> 
> 
> WIth 4 disks it is 25% as 4th disk make the redundancy.
> 
> After that you will lose some because of inconvenient remnants of space
> >that doesn't get used.   Then, there are amounts for superblocks and other
> >aspects of building a filesystem, etc.  I think that tends to be around
> >10%
> >altogether.
> >
> >So, your number seems somewhat probable, offhand, without detailed
> >calculations.
> >
> >What operations did you do to get to that point?   Mine would be an
> >fdisk that makes one slice of the entire device, a bsdlabel that
> >divides the slice in to about 6 partitions (including swap) and
> >a newfs on each partition except swap.
> 
> 
> I only need the array only for one big slice and one partition for data
> storage.
> 
> 
> Thanks for the help
> -- 
> Klaus F. Østergaard, <farremosen(at)gmail dot com>