Date: Wed, 2 Oct 1996 14:54:20 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: avalon@coombs.anu.edu.au (Darren Reed) Cc: jrg@demon.net, mrg@eterna.com.au, hackers@freebsd.org, tech-kern@netbsd.org Subject: Re: VPS mailing list, BSD interest? Message-ID: <199610022154.OAA04828@phaeton.artisoft.com> In-Reply-To: <199610021219.FAA02036@freefall.freebsd.org> from "Darren Reed" at Oct 2, 96 10:18:58 pm
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> Hmmm, having used LVM, seen ccd docs, to me, it should be something > like this: > > +----------------------------------+ > | FFS/UFS/NTFS/LFS/VXFS/EXT2/... | > +------------------+---------+-----+ > | | LVM | | > | disks +---+-----+ CCD | > | | | > | hd* sd* xd* +-----------+ > | | > +----------------------------------+ Ugh. A FS type must be able to express a preference or deny an underlying media type. For instance, FFS should be permitted to prevent you putting it on a device which has Logical Device Attributes of LDA_MAY_GROW or LDA_MAY_SHRINK, since handling of these operations requires that the FS register a callback to allow or veto the operation, depending on whether or not it has handlers. Similarly, JFS/NTFS/LFS/etc. which can handle changing agregation sizes with an LVM facility (adding or deleting PP's from the volume) must call back to determine allowable size change increment. I believe JFS requires a 4M or an 8M increment, in all cases, for instance. This is a highly complex issue. I would warn against a soloution that can be represented as a two dimensional image. 8-(. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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