From owner-freebsd-stable@freebsd.org Sun Jan 29 05:43:54 2017 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 30D48CC27EA for ; Sun, 29 Jan 2017 05:43:54 +0000 (UTC) (envelope-from prvs=0202ebff89=ari@ish.com.au) Received: from fish.ish.com.au (202-161-115-54.static.tpgi.com.au [202.161.115.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id DD4791FF6 for ; Sun, 29 Jan 2017 05:43:52 +0000 (UTC) (envelope-from prvs=0202ebff89=ari@ish.com.au) Received: from [10.242.2.3] (port=63854 helo=Aristedess-MacBook-Pro.local) by fish.ish.com.au with esmtpsa (TLSv1.2:DHE-RSA-AES128-SHA:128) (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1cXiH7-0008SN-03; Sun, 29 Jan 2017 16:43:41 +1100 Subject: Re: Boot partition size To: Warner Losh References: Cc: freebsd-stable From: Aristedes Maniatis Message-ID: <54f66195-2929-ef8c-ac53-deaec574c182@ish.com.au> Date: Sun, 29 Jan 2017 16:43:37 +1100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="rL5axKutVWHgo7raGgiE7St7sv5LQSVqW" X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Jan 2017 05:43:54 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --rL5axKutVWHgo7raGgiE7St7sv5LQSVqW Content-Type: multipart/mixed; boundary="Jsg592IK9vor78sjCEDpr2FWiMIt3B4sk"; protected-headers="v1" From: Aristedes Maniatis To: Warner Losh Cc: freebsd-stable Message-ID: <54f66195-2929-ef8c-ac53-deaec574c182@ish.com.au> Subject: Re: Boot partition size References: In-Reply-To: --Jsg592IK9vor78sjCEDpr2FWiMIt3B4sk Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Thanks for your reply Warner, On 29/1/17 3:50pm, Warner Losh wrote: > Unless you are running on tiny disks, you should use 512kB for maximum > future proofing. Given the bloat that's happened in boot1/boot2 over > the years, this is the only sensible default. Then you ('you' in the very generic FreeBSD committers with permission se= nse) should get the wiki changed (link in my previous email) to give bett= er advice. The advice of 128kB seems bad. More people will be hurt. =20 >> 2. Is there any possible short term future where ZFS volumes can be sh= runk, or will I be replacing every hard disk (or rebuilding the machine f= rom scratch)? > Not easily. However, there's several options available to you: (1) not > upgrading the boot partition That seems contrary to the advice that zpool provides when you upgrade a = pool. It specifically tells you that it is really important to upgrade th= e boot partition. But it doesn't tell you this is impossible due to space= requirements *before* you upgrade the pool. Is your suggestion to continue upgrading the OS, but never upgrade the po= ol? > (2) shrinking a swap partition to snag > some space=20 Yes, except I put my swap into a zvol. I did this when I lost a disk once= with a dedicated swap partition and that caused the system to crash. So = I realised that dedicated swap was a really bad idea and I needed to choo= se between zvol and gmirror. I chose zvol to avoid having one more thing = to check and worry about. > (3) putting a larger boot partition at the 'end' of the > disk where there's usually runt sectors due to how gpart (bogusly > imho, but I've not been successful at advocating this viewpoint) > rounds. There's up to an entire cylinder at the end (though LBAs make > CHS bogus), which might be useful. It's also possible to move the > start of the boot partition to a smaller LBA, which gives us more than > the 44k we currently have. We may also be able to write a smaller GPT > area if we use only a couple of partitions on the disk. I read that the boot partition had to be the first partition on disk. Is = that wrong? > In this case, there's no compelling > reason to upgrade the boot blocks that I can see... A quick look at > freebsd-update shows no calls to gpart or dd, which is necessary to > change them. But if we are using new ZFS code, and we upgrade the zpool, might that no= t require new boot code to be able to boot the system? I've already got one system I upgraded to FreeBSD 11, upgraded the pool o= nce everything looked good, and now I cannot upgrade the boot code. I don= 't want to restart the machine... ever. That's possibly unrealistic, alth= ough I could boot from USB in an emergency I guess. Ari Maniatis --=20 --------------------------> Aristedes Maniatis CEO, ish https://www.ish.com.au GPG fingerprint CBFB 84B4 738D 4E87 5E5C 5EFA EF6A 7D2E 3E49 102A --Jsg592IK9vor78sjCEDpr2FWiMIt3B4sk-- --rL5axKutVWHgo7raGgiE7St7sv5LQSVqW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iEYEARECAAYFAliNgQkACgkQ72p9Lj5JECpUMQCbB4DbCY7KnNFYFhuVc03xhZlU ykwAnjtR3Gb8IAk2r/OyW/weKMHpjJ9f =Busl -----END PGP SIGNATURE----- --rL5axKutVWHgo7raGgiE7St7sv5LQSVqW--