Messages in this thread | | | Date | Mon, 2 Nov 1998 17:20:39 -0600 (CST) | From | Shawn Leas <> | Subject | Re: Volume Managers in Linux |
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Let me first appologize. It sounds like I bash MD as bad code; I just think there's better ways to go about what MD does.
On Mon, 2 Nov 1998, MOLNAR Ingo wrote: > in what way isnt MD clean ... ? And in what way is LVM standard? Can you
First, I would like to say MD is all well and good, and if you ask, "Why is MD not clean?", it is really two questions... 1) Is MD the *clean* way to do what MD does? 2) Is MD cleanly implemented.
I guess I think it fails test #1, but passes #2. I don't think this sort of messiness really belongs wholely in the kern. I like the idea of having the virtualization of an LV in kernel. It allows userland to do it's thing.
Kind of like KGI/GGI. Uhh... Don't mean to start another holy war...
> show me some documentation/standard that specifies how LVM should look > like, apart from vague assertions like "uhm, something like Veritas or > AIX's stuff, or maybe HP's?". > -- mingo
A layer that provides a virtual view of physical disk. One that has VGs [Groups of physical volumes (disks or partitions)], PEs [Extents of said VGs in tunable sizes], and LVs [Logical Volumes] which are made from PEs.
A volume group can have alocation policies [strictly contiguous, whatever] so you can control just how your disk pool, or, VG will allow use. Because LVM is basically at it's core a physical -> logical address remapping mechanism, RAID, mirroring, and all the goodies fit REAL nice in userland.
Wouldn't you like to push all that crap out to userspace?
Both Sun and HP use Veritas's LVM. (http://www.veritas.com/product-info/vm/index.htm)
Heinz's LVM is concepually like it, I think. (http://linux.msede.com/lvm/slides.html)
-Shawn <=========== America Held Hostage ===========> Day 2112 for the poor and the middle class. Day 2131 for the rich and the dead. 810 days remaining in the Raw Deal. <============================================>
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