ZFS With Gpart partitions
krad
kraduk at gmail.com
Tue Jan 3 23:31:02 UTC 2012
There has been.quite a bit of discussion on this already and I think the
safest way is to always 4k align as this works fine on.both drive types
On Jan 3, 2012 4:29 PM, "Jeremy Chadwick" <freebsd at jdc.parodius.com> wrote:
>
> On Tue, Jan 03, 2012 at 03:38:23PM +0100, Peter Maloney wrote:
> > On 01/03/2012 03:34 PM, Peter Maloney wrote:
> > > On 01/03/2012 02:01 PM, Dan Carroll wrote:
> > >> On 3/01/2012 10:27 PM, krad wrote:
> > >>> Just a not you dont appear to be 4k aligned on this drive. As the
> > >>> drive capacity is > 1.5 Tb you probably should be. You will also be
> > >>> ashift=9 as well. This may or may not be a problem for you.
> > >> That was intentional, as I *thought* these drives were not 4k sector
> > >> drives. I am not sure how I am supposed to tell. They are WD RE4
> > >> drives.
> > >> I confess, however to knowing nothing about ashift=9..... Could you
> > >> elaborate?
> > > Read this thread:
> > >
> > > ZFS using 'advanced format drives' with FreeBSD (8.2-RC3)
> > > http://forums.freebsd.org/showthread.php?t=21644
> > >
> > > (and of course don't play around and run the dd command, etc. for
disks
> > > with valuable data on them)
> > >
> > And looking at dmesg or /var/log/messages should probably tell you what
> > your sector size is.
> >
> > eg.
> > # dmesg | grep "da2:"
> >
> > or
> >
> > # grep "da2:" /var/log/messages
> >
> > or
> >
> > # bunzip2 -c /var/log/messages.1.bz2 | grep "da2:"
> > Nov 28 13:59:35 bcnas1 kernel: da2: <ATA ST33000650NS 0002> Fixed Direct
> > Access SCSI-6 device
> > Nov 28 13:59:35 bcnas1 kernel: da2: 600.000MB/s transfers
> > Nov 28 13:59:35 bcnas1 kernel: da2: Command Queueing enabled
> > Nov 28 13:59:35 bcnas1 kernel: da2: 2861588MB (5860533168 *512 byte
> > sectors*: 255H 63S/T 364801C)
>
> This is incorrect. Most 4KB sector drives advertise a logical sector
> size of 512 (this is to maintain/guarantee full compatibility with older
> OSes and existing software), while sometimes advertising a physical
> sector size of 4096. Comparatively, Intel SSDs advertise both a logical
> and physical sector size of 512, even though we all know better.
>
> Use either "camcontrol identify" or "camcontrol inquiry" (which command
> depends on if you're using SATA-via-CAM or native SCSI) to find out. If
> this doesn't work for you, try using smartmontools (if there's a
> difference between logical/physical it will display both, otherwise
> it'll say "logical/physical" literally).
>
> --
> | Jeremy Chadwick jdc at parodius.com |
> | Parodius Networking http://www.parodius.com/ |
> | UNIX Systems Administrator Mountain View, CA, US |
> | Making life hard for others since 1977. PGP 4BD6C0CB |
>
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There has been.quite a bit of discussion on this already and I think the
safest way is to always 4k align as this works fine on.both drive types
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