Date: Tue, 3 Jan 2012 23:31:01 +0000 From: krad <kraduk@gmail.com> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS With Gpart partitions Message-ID: <CALfReyc11ZriFPZmm15YwS5VeA1P4Epub1vyZM%2BfC8X2X0_mHw@mail.gmail.com> In-Reply-To: <20120103162428.GA18661@icarus.home.lan> References: <4F003EB8.6080006@dannysplace.net> <CALfReyfvOCMpBdndf7UYydmGnUqt2cBYWdhYXaOANbQ_CFHoVA@mail.gmail.com> <4F02FC42.1040103@dannysplace.net> <4F0311F2.7050209@brockmann-consult.de> <4F0312DF.8050004@brockmann-consult.de> <20120103162428.GA18661@icarus.home.lan>
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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 On Jan 3, 2012 4:29 PM, "Jeremy Chadwick" <freebsd@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 | > > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" 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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