Thanks Cameron and Alan. Your explanations and examples corrected my mental model of LVM.
On Sat, Nov 30, 2002 at 10:44:00AM +0000, Alan Chandler wrote: | The point of LVM is that you can easily create, resize or delete | these logical volumes without worrying about them being contiguous | within the physical media My original understanding of LVM was that it allowed aggregating multiple disks/partitions into a single logical partition, and that the logical partitions could be dynamically changed. To this extent I was on the right track, but I had thought the logical volumes could only be changed in terms of partitions. That's why I wanted to make a lot of small partitions -- so I could decide later which volume they were a part of :-). | The trick, I think, is to make your decisions on what Volume Groups | to have. Indeed, that was where I was tricked ;-). After reading the HOWTO I didn't really understand the relationship between VG, LV, and the actual partition (according to the partition table). As it turns out, a "Volume Group" is nothing more than a big virtual disk from which I can then carve out virtual partitions (called "logical volumes") which are then mounted at some point in the directory tree. Both VGs and LVs can be dynamically resized (though I'm not certain if LVs can decrease in size or only increase). A VG encapsulates one or more physical disks/partitions and makes them appear as one large storage space to be divided up amongst the LVs. Now that I understand how the physical disks are first aggregated, and then re-divided into logical "partitions" I agree with Cameron that a disk needs no more than one partition on it. When creating a single partition on an x86 machine, the practicality/simplicity of it beats out purity and the MSDOS partition table format is sufficient. I ended up creating a single 20GB partition, and currently have a 5GB /data/media logical volume and a 1GB /data/prjmgmt (for the cvs root and aegis project repository) logical volume. Both are holding ext3 filesystems. It's kinda late now, but I hope I've been clear enough in writing this. I ought to rewrite the explanation better and then post it on my web site and submit it to the HOWTO maintainer. -D -- Failure is not an option. It is bundled with the software. http://dman.ddts.net/~dman/
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