Date: Tue, 3 Jan 2012 15:51:08 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: krad <kraduk@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS With Gpart partitions Message-ID: <20120103235108.GA25691@icarus.home.lan> In-Reply-To: <CALfReyc11ZriFPZmm15YwS5VeA1P4Epub1vyZM%2BfC8X2X0_mHw@mail.gmail.com> 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> <CALfReyc11ZriFPZmm15YwS5VeA1P4Epub1vyZM%2BfC8X2X0_mHw@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, Jan 03, 2012 at 11:31:01PM +0000, krad wrote: > 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). > > 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 Agreed. The question is why FreeBSD isn't using those defaults in its installer. Furthermore, have you tried to actually accomplish this with gpart? I have. I got practically no where. The -a flag doesn't always do the right thing, and with the -b flag you have to "out-smart" internal calculations being made by the software itself. I also had to do the alignment offset at the filesystem level, and not at the actual slice level. E.g.: gpart create -s mbr adaX gpart add -t freebsd adaX gpart create -s bsd adaXs1 gpart add -b 4033 -s {size} -t freebsd-ufs adaXs1 I forget what the result was if I tried to use -b during the first "gpart add", but it kept coming out wrong or simply didn't work. -- | 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 |
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20120103235108.GA25691>