Date: Wed, 09 May 2007 16:14:47 -0500 From: Jonathan Dobbie <jonathan_dobbie@mcad.edu> To: freebsd-geom@freebsd.org Subject: Re: Nesting gvinum? Message-ID: <464239C7.7000606@mcad.edu> In-Reply-To: <20070509205943.GA850@twoflower.idi.ntnu.no> References: <4641DE02.3000706@mcad.edu> <20070509160018.GB22504@keira.kiwi-computer.com> <4641F533.4000101@mcad.edu> <20070509205943.GA850@twoflower.idi.ntnu.no>
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Ulf Lilleengen wrote: > On Wed, May 09, 2007 at 11:22:11AM -0500, Jonathan Dobbie wrote: > >> Rick C. Petty wrote: >> >>> On Wed, May 09, 2007 at 09:43:14AM -0500, Jonathan Dobbie wrote: >>> >>> >>>> I was hoping to have something like md+LVM where I could change the size >>>> of RAID 5 volumes. Could I have a large gvinum raid-5 volume and then >>>> make 3 gvinum volumes on top that could be resized? >>>> >>>> >>> Except for the nesting, this is precisely what gvinum does. Why do you >>> need nesting? Resizing volumes is something gvinum is supposed to be able >>> to do. >>> >>> >>> >> I thought that it could only resize striped volumes? Would you happen >> to have a guide handy? If I, say, wanted to resize usr and log to add >> 20GB to log, could I drop the s0 subdisk from both, resize, readd, sync >> and then repeat for s1 and s2? >> > > You can only make them bigger. I wouldn't bet on it to work for raid5 in gvinum, > but it should work for simple plex organisations, although I really need to test > this better to find out what works and don't. But making gvinum handle this > properly is one of my goals this summer. > > To grow the volume, you can add new subdisks to gvinum, and the plex and volume > of that uses that subdisk will be larger. However, you need to run growfs to > grow the _filesystem_ on top of it. > > To shrink gvinum volumes is not possible, but shouldn't be that difficult to > implement in gvinum for the simplest plex organisations. However, you need to > be able to shrink UFS, and that is not supported. > > If you're looking for another fs, you might want to try ZFS, but remember that > it is quite experimental compared to UFS. > > There are some guides on gvinum out there that isn't completely outdated, and > google are able to find most of them. The handbook also gives a more general > guide to gvinum and vinum. > > Thanks, this confirms what I was thinking. I'm not the adventuresome sort when it comes to servers, so UFS will work fine. We're pretty small, so 20GB will probably be enough for our logs for quite a while. If not, it won't be that hard to back things up for a resize. It'd be awesome if you were able to get things to grow. We could then at least put larger drives in one at a time and then grow the arrays. Good luck on your summer projects, geom seems well thought out. I'm looking forward to seeing where it goes.
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