Date: Wed, 23 Nov 2011 21:44:44 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Lev Serebryakov <lev@freebsd.org> Cc: freebsd-fs@freebsd.org Subject: Re: Does UFS2 send BIO_FLUSH to GEOM when update metadata (with softupdates)? Message-ID: <20111123194444.GE50300@deviant.kiev.zoral.com.ua> In-Reply-To: <1957615267.20111123230026@serebryakov.spb.ru> References: <1957615267.20111123230026@serebryakov.spb.ru>
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--rzUde4Gex/lOR0Yy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Nov 23, 2011 at 11:00:26PM +0400, Lev Serebryakov wrote: > Hello, Freebsd-fs. >=20 > Does UFS2 with softupdates (without journal) issues BIO_FLUSH to > GEOM layer when it need to ensure consistency on on-disk metadata? No. Softupdates do not need flushes. Read about SU in the design and implementation, or standalone article about it. >=20 > Does UFS2 with SU+J issues this command? Again, no. >=20 > geom_raid5 respects this command, but when write log is enabled, it > produces tons of "Unexpected softupate inconsistency" errors on crash. > It seems, that there is no BIO_FLUSH and writes, which should be > synchronous (metadata updates) isn't :( You are making wrong conclusions from the false assumptions. The only requirement of the SU is that writes reported as done by disk driver are indeed safely landed in the involatile storage. --rzUde4Gex/lOR0Yy Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAk7NTSwACgkQC3+MBN1Mb4i44QCbBgbyz0wpxZ2lGj09UAnpX0Ei rWQAoKSRyUstDNyjTDe9MCp+ogyln8pR =OTx7 -----END PGP SIGNATURE----- --rzUde4Gex/lOR0Yy--
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