Date: Tue, 3 Jan 2012 08:24:28 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: Peter Maloney <peter.maloney@brockmann-consult.de> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS With Gpart partitions Message-ID: <20120103162428.GA18661@icarus.home.lan> In-Reply-To: <4F0312DF.8050004@brockmann-consult.de> References: <4F003EB8.6080006@dannysplace.net> <CALfReyfvOCMpBdndf7UYydmGnUqt2cBYWdhYXaOANbQ_CFHoVA@mail.gmail.com> <4F02FC42.1040103@dannysplace.net> <4F0311F2.7050209@brockmann-consult.de> <4F0312DF.8050004@brockmann-consult.de>
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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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