Date: Sat, 19 Apr 2008 23:26:57 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-questions@freebsd.org Subject: Re: gmirror, geli, gjournal performance Message-ID: <fudo32$tsa$1@ger.gmane.org> In-Reply-To: <20080419172100.GA3638@lastamericanempire.com> References: <20080419172100.GA3638@lastamericanempire.com>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigDE19D8B57EF73FC1DF85C3E9 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable hideo wrote: > Hi everyone, >=20 > I was replacing a disk in a gmirror+geli pair and decided to compare > the performance of gmirror+geli+gjournal before adding the new disk. >=20 > When using these three together is the appropriate order to 1) fdisk > and label 2) mirror the disk, 3) geli the partitions, and 4) use the > geli partitions for gjournal label? It depends on what you want to do. To minimize administration overhead=20 I'd modify the sequence like this: gmirror the drives, geli the entire=20 gmirror, then fdisk it, then add gjournal, use UFS labels. Of course,=20 you can never boot from such a thing. > With respect to performance, I find the writes to the gjournal disk > about half as fast, which I expected from the benchmarks I've seen. > However, reading a single file is identical between the two: >=20 > dd if=3D/sofupdates/1.mpg of=3D/dev/null bs=3D1m > 994049168 bytes transferred in 34.858793 secs (28516454 bytes/s= ec) >=20 > dd if=3D/gjournal/1.mpg of=3D/dev/null bs=3D1m > 994049168 bytes transferred in 34.335267 secs (28951258 bytes/s= ec) >=20 > Is this expected? I was under the impression that reads should be > somewhat faster with gjournal. Is geli decryption the limiting > factor here? No, performance with gjournal can at most be as fast as without gjournal = (in reality it will always be infinitesimally slower since there's=20 another layer in GEOM added). --------------enigDE19D8B57EF73FC1DF85C3E9 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFICmOhldnAQVacBcgRAnu2AJ4qhUZWpmZycr4Bx/6qv/6Q+ppu/QCgl934 ENqvmqTpnMvZjssJcP6hWYg= =AJvG -----END PGP SIGNATURE----- --------------enigDE19D8B57EF73FC1DF85C3E9--
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