Shane wrote: > Hello all, > > I'm building a new server which will use a number of disks > and am not sure of the best way to go about the setup. > There will be 4 320gb SATA drives installed at first. I'm > just wondering how to set the system up for upgradability. > I'll be using raid5 but not sure whether to use lvm over > the raid array. > > By upgradability, I'd like to do several things. Adding > another drive of the same size to the array. I understand > reshape can be used here to expand the underlying block > device. Yes, it can. If the block device is the pv of an lvm array, > would that also automatically expand in which I would > create additional lvs in the new space. If this isn't > automatic, are there ways to do it manually? Not automatic AFAIK - but doable. > What about replacing all four drives with larger units. > Say going from 300gbx4 to 500gbx4. Can one replace them > one at a time, going through fail/rebuild as appropriate > and then expand the array into the unused space Yes. or would > one have to reinstall at that point. No None of the requirements above drive you to layering lvm over the top. That's not to say don't do it - but you certainly don't *need* to do it. Pros: * allows snapshots (for consistent backups) * allows various lvm block movements etc... * Can later grow vg to use discrete additional block devices without raid5 grow limitations (eg same-ish size disks etc) Cons: * extra complexity -> risk of bugs/admin errors... * performance impact As an example of the cons: I've just set up lvm2 over my raid5 and whilst testing snapshots, the first thing that happened was a kernel BUG and an oops... David - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
