Date: Tue, 23 Aug 2011 11:23:26 +1000 From: Peter Jeremy <peterjeremy@acm.org> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: ZFS installs on HD with 4k physical blocks without any warning as on 512 block size device Message-ID: <20110823012326.GA29658@server.vk2pj.dyndns.org> In-Reply-To: <j2tbvk$k1q$1@dough.gmane.org> References: <4E4D50CD.5080806@rawbw.com> <CAFHbX1K%2BRuzBKouAbN0%2BSCOSAkGNdgMzC92YN7GeKn_pD=J=tg@mail.gmail.com> <CAO1bj=ZHC0ZMtrQKr3DV8E3rP3gTMHxdF3J2EPAD3wR5dqN%2BkA@mail.gmail.com> <j2tbvk$k1q$1@dough.gmane.org>
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--BXVAT5kNtrzKuDFl Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2011-Aug-22 12:45:08 +0200, Ivan Voras <ivoras@freebsd.org> wrote: >It would be suboptimal but only for the slight waste of space that would= =20 >have otherwise been reclaimed if the block or fragment size remained 512= =20 >or 2K. This waste of space is insignificant for the vast majority of=20 >users and there are no performance penalties, so it seems that switching= =20 >to 4K sectors by default for all file systems would actually be a good ide= a. This is heavily dependent on the size distribution. I can't quickly check for ZFS but I've done some quick checks on UFS. The following are sizes in MB for my copies of the listed trees with different UFS frag size. These include directories but not indirect blocks: 1b 512b 1024b 2048b 4096b 4430 4511 4631 4875 5457 /usr/ncvs 4910 5027 5181 5499 6133 Old FreeBSD SVN repo 299 370 485 733 1252 /usr/ports cheched out from CVS 467 485 509 557 656 /usr/src 8-stable checkout from CVS Note that the ports tree grew by 50% going from 1K to 2K frags and will grow by another 70% going to 4KB frags. Similar issues will be seen when you have lots of small file. --=20 Peter Jeremy --BXVAT5kNtrzKuDFl Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAk5TAQ4ACgkQ/opHv/APuIexBACgrI4ba5mIgbTq/D5fRcQJfyiY F7QAoJxa5P+dDu6kbpUdUoE/LwllWFUJ =4nIA -----END PGP SIGNATURE----- --BXVAT5kNtrzKuDFl--
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