Re: SATA problem

[Bill Hacker <wbh@xxxxxxxxxxxxx>]

Jason M. Leonard wrote:

> On Thu, 31 Mar 2005, Bill Hacker wrote:
>
> > Jaime Andrés Ballesteros wrote:
> >
> > > Ok Bill, thanks for your answer. My SATA is a Seagate 7200.7 with
> > >  120 GB. FreeBSD 5.3 doesn't recognize the geometry of my disk. 
> > > FreeBSD force me to input another geometry and gives me 114 GB 
> > > and i think this cause the problem.
> >
> >
> > Nope.  That is about all you will get.  Working with a pair of 
> > Western Digital 120 GB PATA the last 2 days, get about 114.4 GB 
> > with either FreeBSD or DFLY.  200 GB Maxtors, PATA or SATA give me 
> > about 190 GB or so.
> >
> > Few HDD can (or should) give you 100% of the theorecticaly 
> > available area.
>
>
> For marketing purposes 1G == 1000M, so with (120 x 1000)/1024 we're 
> looking at a theoretically available area of 117G.  No one really 
> makes 120G (117G) or 200G (195G) hard drives.
>
>
> :Fu zz

Yes and 'not quite'.

Look at the slices and note that there is 'unused' (and unusable)
space showing.  Drives will reserve space for a pool of replacements for
bad blocks.  An OS will reserve a bit more.

Put the SCSI variant of any of the above on a sophisticated SCSI RAID
controller and use it unformated as a raw block device - the best way
for true hot-swap, wherein the MBR and partition table are stored in the
controller's NVRAM.  You can get a lot closer to the published capacity.

But such controllers are far and away more expensive than the miniscule
extra space one might gain.  That's not why you buy them.

Bill