Date: Tue, 25 Jun 2013 16:31:20 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Frank Leonhardt <frank2@fjl.co.uk> Cc: freebsd-doc@freebsd.org Subject: Re: Handbook obsolescence scan: "The vinum Volume Manager" Message-ID: <alpine.BSF.2.00.1306251618540.67375@wonkity.com> In-Reply-To: <51C9FF66.6020302@fjl.co.uk> References: <alpine.BSF.2.00.1306250933560.64224@wonkity.com> <51C9CD3B.4090001@fjl.co.uk> <alpine.BSF.2.00.1306251143080.65313@wonkity.com> <51C9FF66.6020302@fjl.co.uk>
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On Tue, 25 Jun 2013, Frank Leonhardt wrote: > Couldn't agree more! In fact the whole disk mirroring thing still > confuses me, as there are too many options and no guide for choosing > between them. As far as I understand it, gmirror is the way to go in > most cases because you end up with two identical drives, either of > which can be salvaged from the wreckage after a crash, stuck in to > another PC and booted. ZFS is the solution if you want to spread lots > of data across lots of drives. ZFS can do mirrors, too, and almost everything else. Its weakness now is that it is relatively memory hungry. So I would advise this: gmirror(8) for data safety on machines with relatively limited memory. graid(8) for software BIOS RAID. ZFS for mirrors or more typical RAID arrays on machines with 4G of memory or more. > Actually, in practical terms, I don't see why ZFS is better than pairs > (or threes) of gmirrored drives mounted on to one file system in the > traditional way. Perhaps I just don't get it, or perhaps I'm just too > traditional to give up on the idea that it's good to know which drive > a particular file is on. It's RAID, so you get more space than mirrors, and possibly better performance for some things. ZFS RAID-Z1 (and -Z2, -Z3) have a lower vacuum coefficient than RAID-5. There are lots of nifty features, like being able to add storage without reformatting. There are other options, but I suspect the three above cover most of the needs and are what we should be suggesting to new users in the Handbook.home | help
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