Messages in this thread | | | From | Werner Almesberger <> | Subject | Re: Toronto Filsystem? | Date | Tue, 3 Mar 1998 16:54:57 +0100 (MET) |
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Trever Adams wrote: >> From: "Benjamin C.R. LaHaise" [...] >> Actually, this is easier than it seems. A simple restriction that makes >> everything work well is to require that all underlying layers be made >> read-only, which avoids a mess of consistency problems. Then, use a top >> layer that supports sparse files. Reading a file becomes: try layer one - >> oh, not there; try layer 2... No, I don't have working code yet. [...] > Not cool at all. Once the original file owner updates the file (say the > group agrees on a new standard, or root updates the file) any way but > clean implimentation and write of the entire modified file becomes > corrupted.
So you'd have to make "per-block COW" behaviour a mount option. With some media (e.g. CD-ROM) you can be very sure that they won't change, so such a shortcut is perfectly valid.
- Werner
-- _________________________________________________________________________ / Werner Almesberger, DI-ICA,EPFL,CH werner.almesberger@lrc.di.epfl.ch / /_IN_R_131__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/
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