File system blocks alignment
Pieter de Goeje
pieter at degoeje.nl
Mon Dec 28 20:45:21 UTC 2009
On Monday 28 December 2009 13:30:22 Alexander Motin wrote:
> Miroslav Lachman wrote:
> > Alexander Motin wrote:
> >> Thomas Backman wrote:
> >>> On Dec 25, 2009, at 11:58 AM, Alexander Motin wrote:
> >> |>> Recently WD released first series of ATA disks with increased
> >> physical
> >>>> sector size. It makes writes not matching with 4K blocks inefficient
> >>>> there.
> >>> They don't expose this to the OS, though (not by default, anyway),
> >>> but chop it up into 8 512-byte sectors for compatibility reasons.
> >>> Just thought I'd point that out - I'm not even sure if you can get
> >>> them to *not* do the compatibility thing and expose 4k-sized sectors.
> >> Latest ATA-8 specification allows drive to report both logical (512B)
> >> and physical (4KB) sector sizes. ada driver able to fetch and report
> >> that info to GEOM. If these drives not reporting it yet (are you really
> >> sure?), it is only question of their firmware.
> > There is an article about 4k sectors
> > http://www.anandtech.com/storage/showdoc.aspx?i=3691
> > It is completely hidden to OS in first versions.
> Thanks for the link, but all I see there is "but at this point there’s
> no such tool". IMHO it doesn't meet it is not reported.
> We just need somebody with that drive to run on it `camcontrol identify`
> from the fresh system and report what he sees.
I've just ordered one of these disks. I expect it to arrive in a couple of
days. Will let you know what it says when I have it :)
More information about the freebsd-arch