Date: Wed, 2 Oct 1996 08:55:28 -0500 (CDT) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: mrg@eterna.com.au (matthew green) Cc: kpneal@pobox.com, gibbs@freefall.freebsd.org, thorpej@nas.nasa.gov, phk@critter.tfs.com, greywolf@siva.captech.com, hackers@freebsd.org, tech-kern@netbsd.org, buhrow@cats.ucsc.edu Subject: Re: VPS mailing list, BSD interest? Message-ID: <199610021355.IAA05107@brasil.moneng.mei.com> In-Reply-To: <199610020544.PAA18948@eterna.com.au> from "matthew green" at Oct 2, 96 03:44:14 pm
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> i like parts of ODS: it keeps state in dedicated partitions on the > disk, a metadevice db "replica". you create several of these partitions > on your disks and it uses them to keep state -- each one is independant > or the others. This works pretty well. > i also like the model of ODS (as under solaris 2): > - a metadevice acts like a normal disk partition > - a metadevice can be composed of any number of real partitions > or metadevices, either concatenated or striped, or mirrored. > > you create a mirrored stripe by creating two (or three -- ODS has an, > IMO, stpuid limit) stripes and then mirroring these two metadevices. > > recent ODS versions include raid5 support, file system extensions, etc. > > i'm fairly conversant in ODS if anyone has other questions. ODS has (IMHO) a disadvantage... each metadevice is only allowed to be a partition. CCD allows you to stick a disklabel on its "metadevice" and you can have partition_s_. This is maybe marginally useful, but I happen to like it. It allows me to build an I/O "policy" where I stripe two drives together and simply consider the aggregate to be a faster drive... and then I partition it up. It requires less complexity in ccd.conf. *shrug* But.. if I could have something with all the features of ODS under *BSD.. and none of the slowdowns... I would in a minute. ... JG
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