Date: Tue, 10 Jun 1997 11:23:52 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: gpalmer@FreeBSD.ORG (Gary Palmer) Cc: jkh@time.cdrom.com, current@FreeBSD.ORG Subject: Re: overclocking Message-ID: <199706101823.LAA02815@phaeton.artisoft.com> In-Reply-To: <18340.865926916@orion.webspan.net> from "Gary Palmer" at Jun 10, 97 03:15:16 am
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> > Most importantly, I'd like to be able to migrate off and dismount a > > drive from a ccd or add one dynamically, automagically resizing the > > filesystem on it in either case, before I could ever consider it close > > to mission critical safe. > > Question: How do you plan to dynamically resize a UFS filesystem? I > think it'd take a LOT of work, as you'd have to ensure that your > filesystem had all the data (i.e. inode blocks, cylinder groups, etc) > associated with each file, on the same drive as the file, and that the > file would basically have to fit on the drive (this is assuming you > don't want to write a new filesystem). You write a fragger and a defragger, and frag the heck out of it when shrinking (pack it at the front of the disk) and "defrag" it back to a wide dispersion after setting the new size. You can also add cylinder groups, but you need to "defrag" after that as well to get a uniform hash dispersion. It's relatively brain-damaged. If you plan on doing this, it's better to define a "PP" and "LP" aware FS instead of one that relies on hashing over the entire space. This is a complex task. 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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