Date: Sun, 25 May 2014 12:32:31 -0400 From: Allan Jude <allanjude@freebsd.org> To: Nathan Whitehorn <nwhitehorn@freebsd.org>, Kurt Lidl <lidl@pix.net> Cc: freebsd-sysinstall@freebsd.org, "Michael W. Lucas" <mwlucas@michaelwlucas.com> Subject: Re: bin/164281: bsdinstall(8): please allow sysinstall as installer option Message-ID: <53821B1F.8000509@freebsd.org> In-Reply-To: <538219DA.3040702@freebsd.org> References: <201404151630.s3FGU0Zg026166@freefall.freebsd.org> <CAM9wqY8Bn9yQvMbpMdg1wcVhx5AGgK6rP1tkh9qccDhWZaU9Kw@mail.gmail.com> <012501cf5f1f$c5e7c740$51b755c0$@FreeBSD.org> <5358223B.1090408@gmail.com> <535827AC.3040503@allanjude.com> <53582CC4.2080808@freebsd.org> <53583D5C.5020506@pix.net> <53583DB8.1080905@freebsd.org> <20140423230210.GA20429@pix.net> <538219DA.3040702@freebsd.org>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --9QGd71pNw2I59eJ4Iv9Rc4odImbHWeRg2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2014-05-25 12:27, Nathan Whitehorn wrote: >=20 > I'm (finally) integrating these patches now. Could you remind me what > the point of the gnop is? I'm not sure I get it. > -Nathan The 'gnop -S 4096 <device>' makes a virtual device that has a sector size of 4096 bytes. This causes ZFS to set ashift=3D12 even for devices that mis-advertise (lie about) their sector size. There is no real harm in using 4k sectors on a 512b sector device, but using 512b sectors on a 4k device will cause write amplification (read-modify-write) since the device will have to deal with it as a partial block update. Additionally, the sector size can only be set at pool creation time, even if you have have 512b sector devices, you'll want to create your pool as 4k, so that in the future when you add additional devices, or replace failed devices, the 4k sector devices will be supported. ZFS complains loudly when you try to add mis-matched sector size devices to a pool. --=20 Allan Jude --9QGd71pNw2I59eJ4Iv9Rc4odImbHWeRg2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTghsiAAoJEJrBFpNRJZKfZCcP/2xVojtb4xlmoE+Ekb7iUoBA dBok2fQ7987hwM20ZYz2rPSEob/qh9m1OuFF5Q94XYUEERf9n8P+3A3kyaBN05lF MnmoJ9DR4Ai8Qe81g+kre7Qzj7wZpQ27ZwOYtbhucjkNHTXMjpHGlRfgMidoMpTN A+Q+ZluuX0NwES1aFT2xOAeADOiEw+aIBRTZDBS3R2AuY2/So7vLWNTG7i4rd/74 wYqQFp1JPkoec7/qiYuLUdAvqLbpHDsjXYAzoSKQfeNoJP0QNsMWhCHVS0AUrKlJ 9F0KRvOHhUSoJNa0N1X9nu/v8fNODcow0LMuuCcddn9924UnB/6u4cOS3foIRbEM 8zLmp9Ke+6iVSluSjqgxrwnIoqe0sLT/zoLzV7LbkLoG6Tf2FqUn7s0oudvxDp0I uK6K97M2rc1L5b+bCrr/8jZEC8urFNRQ07RoJZJYXz5HaFgsUdXvXeF27fXUWzrU MKIgM5UF/qORFbUu/Vn6Vp/WVXecKNMXSkCZyiCmYHP8R3yolKwVYrcABI6VymYu 3Y7LgsX9aZi+SG73AznBzF6f+F+ti09X6GvF742foCAj8PbH2d/OsvbeV4fKvnuu 122HqH+X0en93yQEYrWB7ph41yW1mu8iurx74LtpnUx0lq02K7FZR2mbaPCpLaFG pzi41c9etf2JP8maH4eN =wugw -----END PGP SIGNATURE----- --9QGd71pNw2I59eJ4Iv9Rc4odImbHWeRg2--
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